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<!-- Creation Date      : 2020-03-10T12:38:49.2157981+00:00 -->
<!-- Version            : 5.0.1.369 -->
<!-- Package ID         : a0f4cac9069d4963a096e5f0f5bb8ecc -->
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    <link:loc xlink:href="psn-20191231.xsd#psn_IncomeTaxReconciliationTransactionCosts" xlink:type="locator" xlink:label="psn_IncomeTaxReconciliationTransactionCosts" />
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    <link:loc xlink:href="psn-20191231.xsd#psn_DeferredTaxAssetsLeaseLiability" xlink:type="locator" xlink:label="psn_DeferredTaxAssetsLeaseLiability" />
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    <link:label xml:lang="en-US" xlink:label="psn_DeferredTaxLiabilitiesRevenueAndCostRecognition_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Deferred tax liabilities revenue and cost recognition.</link:label>
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    <link:loc xlink:href="psn-20191231.xsd#psn_LongTermEmployeeIncentives" xlink:type="locator" xlink:label="psn_LongTermEmployeeIncentives" />
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    <link:loc xlink:href="psn-20191231.xsd#psn_LitigationClaimSettlementRelatedExpenseIncome" xlink:type="locator" xlink:label="psn_LitigationClaimSettlementRelatedExpenseIncome" />
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    <link:loc xlink:href="psn-20191231.xsd#psn_SaleLeasebackTransactionAmortizationOfDeferredGain" xlink:type="locator" xlink:label="psn_SaleLeasebackTransactionAmortizationOfDeferredGain" />
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    <link:loc xlink:href="psn-20191231.xsd#psn_OtherReconciliationFromNetIncomeToAdjustedEBITDA" xlink:type="locator" xlink:label="psn_OtherReconciliationFromNetIncomeToAdjustedEBITDA" />
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    <link:label xml:lang="en-US" xlink:label="dei_DocumentFiscalYearFocus_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Document Fiscal Year Focus</link:label>
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    <link:label xml:lang="en-US" xlink:label="dei_EntityInteractiveDataCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Entity Interactive Data Current</link:label>
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    <link:loc xlink:href="https://xbrl.sec.gov/dei/2019/dei-2019-01-31.xsd#dei_EntityWellKnownSeasonedIssuer" xlink:type="locator" xlink:label="dei_EntityWellKnownSeasonedIssuer" />
    <link:label xml:lang="en-US" xlink:label="dei_EntityWellKnownSeasonedIssuer_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Entity Well-known Seasoned Issuer</link:label>
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    <link:label xml:lang="en-US" xlink:label="dei_EntityWellKnownSeasonedIssuer_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Entity Well Known Seasoned Issuer</link:label>
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2019/dei-2019-01-31.xsd#dei_EntityVoluntaryFilers" xlink:type="locator" xlink:label="dei_EntityVoluntaryFilers" />
    <link:label xml:lang="en-US" xlink:label="dei_EntityVoluntaryFilers_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Entity Voluntary Filers</link:label>
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    <link:label xml:lang="en-US" xlink:label="dei_EntityVoluntaryFilers_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Entity Voluntary Filers</link:label>
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2019/dei-2019-01-31.xsd#dei_CurrentFiscalYearEndDate" xlink:type="locator" xlink:label="dei_CurrentFiscalYearEndDate" />
    <link:label xml:lang="en-US" xlink:label="dei_CurrentFiscalYearEndDate_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Current Fiscal Year End Date</link:label>
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    <link:label xml:lang="en-US" xlink:label="dei_CurrentFiscalYearEndDate_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Current Fiscal Year End Date</link:label>
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2019/dei-2019-01-31.xsd#dei_EntityFilerCategory" xlink:type="locator" xlink:label="dei_EntityFilerCategory" />
    <link:label xml:lang="en-US" xlink:label="dei_EntityFilerCategory_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Entity Filer Category</link:label>
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    <link:loc xlink:href="https://xbrl.sec.gov/dei/2019/dei-2019-01-31.xsd#dei_EntityCommonStockSharesOutstanding" xlink:type="locator" xlink:label="dei_EntityCommonStockSharesOutstanding" />
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    <link:loc xlink:href="https://xbrl.sec.gov/dei/2019/dei-2019-01-31.xsd#dei_EntityPublicFloat" xlink:type="locator" xlink:label="dei_EntityPublicFloat" />
    <link:label xml:lang="en-US" xlink:label="dei_EntityPublicFloat_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Entity Public Float</link:label>
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    <link:label xml:lang="en-US" xlink:label="dei_EntityPublicFloat_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Entity Public Float</link:label>
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2019/dei-2019-01-31.xsd#dei_EntityShellCompany" xlink:type="locator" xlink:label="dei_EntityShellCompany" />
    <link:label xml:lang="en-US" xlink:label="dei_EntityShellCompany_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Entity Shell Company</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="dei_EntityShellCompany" xlink:to="dei_EntityShellCompany_lbl" />
    <link:label xml:lang="en-US" xlink:label="dei_EntityShellCompany_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Entity Shell Company</link:label>
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2019/dei-2019-01-31.xsd#dei_EntitySmallBusiness" xlink:type="locator" xlink:label="dei_EntitySmallBusiness" />
    <link:label xml:lang="en-US" xlink:label="dei_EntitySmallBusiness_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Entity Small Business</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="dei_EntitySmallBusiness" xlink:to="dei_EntitySmallBusiness_lbl" />
    <link:label xml:lang="en-US" xlink:label="dei_EntitySmallBusiness_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Entity Small Business</link:label>
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2019/dei-2019-01-31.xsd#dei_EntityEmergingGrowthCompany" xlink:type="locator" xlink:label="dei_EntityEmergingGrowthCompany" />
    <link:label xml:lang="en-US" xlink:label="dei_EntityEmergingGrowthCompany_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Entity Emerging Growth Company</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="dei_EntityEmergingGrowthCompany" xlink:to="dei_EntityEmergingGrowthCompany_lbl" />
    <link:label xml:lang="en-US" xlink:label="dei_EntityEmergingGrowthCompany_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Entity Emerging Growth Company</link:label>
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2019/dei-2019-01-31.xsd#dei_EntityFileNumber" xlink:type="locator" xlink:label="dei_EntityFileNumber" />
    <link:label xml:lang="en-US" xlink:label="dei_EntityFileNumber_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Entity File Number</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="dei_EntityFileNumber" xlink:to="dei_EntityFileNumber_lbl" />
    <link:label xml:lang="en-US" xlink:label="dei_EntityFileNumber_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Entity File Number</link:label>
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2019/dei-2019-01-31.xsd#dei_EntityIncorporationStateCountryCode" xlink:type="locator" xlink:label="dei_EntityIncorporationStateCountryCode" />
    <link:label xml:lang="en-US" xlink:label="dei_EntityIncorporationStateCountryCode_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Entity Incorporation, State or Country Code</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="dei_EntityIncorporationStateCountryCode" xlink:to="dei_EntityIncorporationStateCountryCode_lbl" />
    <link:label xml:lang="en-US" xlink:label="dei_EntityIncorporationStateCountryCode_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Entity Incorporation State Country Code</link:label>
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2019/dei-2019-01-31.xsd#dei_EntityTaxIdentificationNumber" xlink:type="locator" xlink:label="dei_EntityTaxIdentificationNumber" />
    <link:label xml:lang="en-US" xlink:label="dei_EntityTaxIdentificationNumber_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Entity Tax Identification Number</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="dei_EntityTaxIdentificationNumber" xlink:to="dei_EntityTaxIdentificationNumber_lbl" />
    <link:label xml:lang="en-US" xlink:label="dei_EntityTaxIdentificationNumber_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Entity Tax Identification Number</link:label>
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2019/dei-2019-01-31.xsd#dei_EntityAddressAddressLine1" xlink:type="locator" xlink:label="dei_EntityAddressAddressLine1" />
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    <link:label xml:lang="en-US" xlink:label="dei_EntityAddressAddressLine1_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Entity Address Address Line1</link:label>
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2019/dei-2019-01-31.xsd#dei_EntityAddressCityOrTown" xlink:type="locator" xlink:label="dei_EntityAddressCityOrTown" />
    <link:label xml:lang="en-US" xlink:label="dei_EntityAddressCityOrTown_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Entity Address, City or Town</link:label>
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    <link:label xml:lang="en-US" xlink:label="dei_EntityAddressCityOrTown_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Entity Address City Or Town</link:label>
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2019/dei-2019-01-31.xsd#dei_EntityAddressStateOrProvince" xlink:type="locator" xlink:label="dei_EntityAddressStateOrProvince" />
    <link:label xml:lang="en-US" xlink:label="dei_EntityAddressStateOrProvince_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Entity Address, State or Province</link:label>
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    <link:label xml:lang="en-US" xlink:label="dei_EntityAddressStateOrProvince_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Entity Address State Or Province</link:label>
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2019/dei-2019-01-31.xsd#dei_EntityAddressPostalZipCode" xlink:type="locator" xlink:label="dei_EntityAddressPostalZipCode" />
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    <link:label xml:lang="en-US" xlink:label="dei_EntityAddressPostalZipCode_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Entity Address Postal Zip Code</link:label>
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2019/dei-2019-01-31.xsd#dei_CityAreaCode" xlink:type="locator" xlink:label="dei_CityAreaCode" />
    <link:label xml:lang="en-US" xlink:label="dei_CityAreaCode_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel">City Area Code</link:label>
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    <link:label xml:lang="en-US" xlink:label="dei_CityAreaCode_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">City Area Code</link:label>
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2019/dei-2019-01-31.xsd#dei_LocalPhoneNumber" xlink:type="locator" xlink:label="dei_LocalPhoneNumber" />
    <link:label xml:lang="en-US" xlink:label="dei_LocalPhoneNumber_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel">Local Phone Number</link:label>
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    <link:label xml:lang="en-US" xlink:label="dei_LocalPhoneNumber_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Local Phone Number</link:label>
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2019/dei-2019-01-31.xsd#dei_DocumentAnnualReport" xlink:type="locator" xlink:label="dei_DocumentAnnualReport" />
    <link:label xml:lang="en-US" xlink:label="dei_DocumentAnnualReport_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Document Annual Report</link:label>
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    <link:label xml:lang="en-US" xlink:label="dei_DocumentAnnualReport_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Document Annual Report</link:label>
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    <link:label xml:lang="en-US" xlink:label="dei_DocumentTransitionReport_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Document Transition Report</link:label>
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    <link:label xml:lang="en-US" xlink:label="dei_DocumentTransitionReport_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Document Transition Report</link:label>
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2019/dei-2019-01-31.xsd#dei_Security12bTitle" xlink:type="locator" xlink:label="dei_Security12bTitle" />
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    <link:label xml:lang="en-US" xlink:label="dei_Security12bTitle_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Security12b Title</link:label>
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2019/dei-2019-01-31.xsd#dei_TradingSymbol" xlink:type="locator" xlink:label="dei_TradingSymbol" />
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    <link:loc xlink:href="https://xbrl.sec.gov/dei/2019/dei-2019-01-31.xsd#dei_SecurityExchangeName" xlink:type="locator" xlink:label="dei_SecurityExchangeName" />
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    <link:loc xlink:href="psn-20191231.xsd#psn_AccruedExpensesAndOtherCurrentLiabilities" xlink:type="locator" xlink:label="psn_AccruedExpensesAndOtherCurrentLiabilities" />
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    <link:label xml:lang="en-US" xlink:label="us-gaap_AssetsCurrentAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Current assets</link:label>
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    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_CashAndCashEquivalentsAtCarryingValue" xlink:to="us-gaap_CashAndCashEquivalentsAtCarryingValue_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_CashAndCashEquivalentsAtCarryingValue_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Cash And Cash Equivalents At Carrying Value</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_RestrictedCashAndInvestmentsCurrent" xlink:type="locator" xlink:label="us-gaap_RestrictedCashAndInvestmentsCurrent" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_RestrictedCashAndInvestmentsCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Restricted cash and investments</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_RestrictedCashAndInvestmentsCurrent" xlink:to="us-gaap_RestrictedCashAndInvestmentsCurrent_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_RestrictedCashAndInvestmentsCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Restricted Cash And Investments Current</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AccountsReceivableNetCurrent" xlink:type="locator" xlink:label="us-gaap_AccountsReceivableNetCurrent" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_AccountsReceivableNetCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Accounts receivable, net (including $180,325 and $166,355 Accounts receivable of consolidated joint ventures, net)</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AccountsReceivableNetCurrent" xlink:to="us-gaap_AccountsReceivableNetCurrent_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_AccountsReceivableNetCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Accounts Receivable Net Current</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ContractWithCustomerAssetNetCurrent" xlink:type="locator" xlink:label="us-gaap_ContractWithCustomerAssetNetCurrent" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ContractWithCustomerAssetNetCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/positiveLabel">Contract assets (including $21,270 and $26,458 Contract assets of consolidated joint ventures)</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ContractWithCustomerAssetNetCurrent" xlink:to="us-gaap_ContractWithCustomerAssetNetCurrent_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ContractWithCustomerAssetNetCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Contract With Customer Asset Net Current</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PrepaidExpenseAndOtherAssetsCurrent" xlink:type="locator" xlink:label="us-gaap_PrepaidExpenseAndOtherAssetsCurrent" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_PrepaidExpenseAndOtherAssetsCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Prepaid expenses and other current assets (including $11,837 and $11,182 Prepaid expenses and other current assets of consolidated joint ventures)</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PrepaidExpenseAndOtherAssetsCurrent" xlink:to="us-gaap_PrepaidExpenseAndOtherAssetsCurrent_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_PrepaidExpenseAndOtherAssetsCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Prepaid Expense And Other Assets Current</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AssetsCurrent" xlink:type="locator" xlink:label="us-gaap_AssetsCurrent" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_AssetsCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Total current assets</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AssetsCurrent" xlink:to="us-gaap_AssetsCurrent_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_AssetsCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Assets Current</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PropertyPlantAndEquipmentNet" xlink:type="locator" xlink:label="us-gaap_PropertyPlantAndEquipmentNet" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_PropertyPlantAndEquipmentNet_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/positiveLabel">Property and equipment, net (including $2,561 and $2,945 Property and equipment of consolidated joint ventures, net)</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PropertyPlantAndEquipmentNet" xlink:to="us-gaap_PropertyPlantAndEquipmentNet_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_PropertyPlantAndEquipmentNet_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Property Plant And Equipment Net</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OperatingLeaseRightOfUseAsset" xlink:type="locator" xlink:label="us-gaap_OperatingLeaseRightOfUseAsset" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_OperatingLeaseRightOfUseAsset_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Right of use assets, operating leases</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OperatingLeaseRightOfUseAsset" xlink:to="us-gaap_OperatingLeaseRightOfUseAsset_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_OperatingLeaseRightOfUseAsset_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Operating Lease Right Of Use Asset</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_Goodwill" xlink:type="locator" xlink:label="us-gaap_Goodwill" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_Goodwill_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Goodwill</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_Goodwill" xlink:to="us-gaap_Goodwill_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_Goodwill_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Goodwill</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures" xlink:type="locator" xlink:label="us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Investments in and advances to unconsolidated joint ventures</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures" xlink:to="us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Investments In Affiliates Subsidiaries Associates And Joint Ventures</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IntangibleAssetsNetExcludingGoodwill" xlink:type="locator" xlink:label="us-gaap_IntangibleAssetsNetExcludingGoodwill" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_IntangibleAssetsNetExcludingGoodwill_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Intangible assets, net</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_IntangibleAssetsNetExcludingGoodwill" xlink:to="us-gaap_IntangibleAssetsNetExcludingGoodwill_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_IntangibleAssetsNetExcludingGoodwill_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Intangible Assets Net Excluding Goodwill</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DeferredIncomeTaxAssetsNet" xlink:type="locator" xlink:label="us-gaap_DeferredIncomeTaxAssetsNet" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DeferredIncomeTaxAssetsNet_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Deferred tax assets</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DeferredIncomeTaxAssetsNet" xlink:to="us-gaap_DeferredIncomeTaxAssetsNet_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DeferredIncomeTaxAssetsNet_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Deferred Income Tax Assets Net</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OtherAssetsNoncurrent" xlink:type="locator" xlink:label="us-gaap_OtherAssetsNoncurrent" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_OtherAssetsNoncurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Other noncurrent assets</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OtherAssetsNoncurrent" xlink:to="us-gaap_OtherAssetsNoncurrent_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_OtherAssetsNoncurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Other Assets Noncurrent</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_Assets" xlink:type="locator" xlink:label="us-gaap_Assets" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_Assets_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Total assets</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_Assets" xlink:to="us-gaap_Assets_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_Assets_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Assets</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LiabilitiesAndStockholdersEquityAbstract" xlink:type="locator" xlink:label="us-gaap_LiabilitiesAndStockholdersEquityAbstract" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LiabilitiesAndStockholdersEquityAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Liabilities, Redeemable Common Stock, and Shareholder&#8217;s Equity (Deficit)</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LiabilitiesAndStockholdersEquityAbstract" xlink:to="us-gaap_LiabilitiesAndStockholdersEquityAbstract_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LiabilitiesAndStockholdersEquityAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Liabilities And Stockholders Equity [Abstract]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LiabilitiesCurrentAbstract" xlink:type="locator" xlink:label="us-gaap_LiabilitiesCurrentAbstract" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LiabilitiesCurrentAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Current liabilities</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LiabilitiesCurrentAbstract" xlink:to="us-gaap_LiabilitiesCurrentAbstract_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LiabilitiesCurrentAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Liabilities Current [Abstract]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AccountsPayableCurrent" xlink:type="locator" xlink:label="us-gaap_AccountsPayableCurrent" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_AccountsPayableCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Accounts payable (including $87,914 and $85,869 Accounts payable of consolidated joint ventures)</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AccountsPayableCurrent" xlink:to="us-gaap_AccountsPayableCurrent_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_AccountsPayableCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Accounts Payable Current</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_AccruedExpensesAndOtherCurrentLiabilities_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/positiveLabel">Accrued expenses and other current liabilities (including $73,209 and $74,857 Accrued expenses and other current liabilities of consolidated joint ventures)</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_AccruedExpensesAndOtherCurrentLiabilities_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Accrued Expenses And Other Current Liabilities</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ContractWithCustomerLiabilityCurrent" xlink:type="locator" xlink:label="us-gaap_ContractWithCustomerLiabilityCurrent" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ContractWithCustomerLiabilityCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/positiveLabel">Contract liabilities (including $38,706 and $32,638 Contract liabilities of consolidated joint ventures)</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ContractWithCustomerLiabilityCurrent" xlink:to="us-gaap_ContractWithCustomerLiabilityCurrent_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ContractWithCustomerLiabilityCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Contract With Customer Liability Current</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OperatingLeaseLiabilityCurrent" xlink:type="locator" xlink:label="us-gaap_OperatingLeaseLiabilityCurrent" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_OperatingLeaseLiabilityCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Short-term lease liabilities, operating leases</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OperatingLeaseLiabilityCurrent" xlink:to="us-gaap_OperatingLeaseLiabilityCurrent_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_OperatingLeaseLiabilityCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Operating Lease Liability Current</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_TaxesPayableCurrent" xlink:type="locator" xlink:label="us-gaap_TaxesPayableCurrent" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_TaxesPayableCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Income taxes payable</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_TaxesPayableCurrent" xlink:to="us-gaap_TaxesPayableCurrent_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_TaxesPayableCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Taxes Payable Current</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LiabilitiesCurrent" xlink:type="locator" xlink:label="us-gaap_LiabilitiesCurrent" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LiabilitiesCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Total current liabilities</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LiabilitiesCurrent" xlink:to="us-gaap_LiabilitiesCurrent_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LiabilitiesCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Liabilities Current</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_LongTermEmployeeIncentives_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Long-term employee incentives</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_LongTermEmployeeIncentives_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Long Term Employee Incentives</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_SaleLeasebackTransactionDeferredGainNet" xlink:type="locator" xlink:label="us-gaap_SaleLeasebackTransactionDeferredGainNet" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_SaleLeasebackTransactionDeferredGainNet_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Deferred gain resulting from sale-leaseback transactions</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SaleLeasebackTransactionDeferredGainNet" xlink:to="us-gaap_SaleLeasebackTransactionDeferredGainNet_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_SaleLeasebackTransactionDeferredGainNet_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Sale Leaseback Transaction Deferred Gain Net</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LongTermDebt" xlink:type="locator" xlink:label="us-gaap_LongTermDebt" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LongTermDebt_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Long-term debt</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LongTermDebt" xlink:to="us-gaap_LongTermDebt_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LongTermDebt_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Long Term Debt</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OperatingLeaseLiabilityNoncurrent" xlink:type="locator" xlink:label="us-gaap_OperatingLeaseLiabilityNoncurrent" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_OperatingLeaseLiabilityNoncurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Long-term lease liabilities, operating leases</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OperatingLeaseLiabilityNoncurrent" xlink:to="us-gaap_OperatingLeaseLiabilityNoncurrent_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_OperatingLeaseLiabilityNoncurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Operating Lease Liability Noncurrent</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DeferredIncomeTaxLiabilitiesNet" xlink:type="locator" xlink:label="us-gaap_DeferredIncomeTaxLiabilitiesNet" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DeferredIncomeTaxLiabilitiesNet_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Deferred tax liabilities</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_DeferredIncomeTaxLiabilitiesNet_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Deferred Income Tax Liabilities Net</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OtherLiabilitiesNoncurrent" xlink:type="locator" xlink:label="us-gaap_OtherLiabilitiesNoncurrent" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_OtherLiabilitiesNoncurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Other long-term liabilities</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OtherLiabilitiesNoncurrent" xlink:to="us-gaap_OtherLiabilitiesNoncurrent_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_OtherLiabilitiesNoncurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Other Liabilities Noncurrent</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_Liabilities" xlink:type="locator" xlink:label="us-gaap_Liabilities" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_Liabilities_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Total liabilities</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_Liabilities" xlink:to="us-gaap_Liabilities_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_Liabilities_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Liabilities</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CommitmentsAndContingencies" xlink:type="locator" xlink:label="us-gaap_CommitmentsAndContingencies" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_CommitmentsAndContingencies_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Contingencies (Note 15)</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_CommitmentsAndContingencies" xlink:to="us-gaap_CommitmentsAndContingencies_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_CommitmentsAndContingencies_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Commitments And Contingencies</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_TemporaryEquityCarryingAmountAttributableToParent" xlink:type="locator" xlink:label="us-gaap_TemporaryEquityCarryingAmountAttributableToParent" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_TemporaryEquityCarryingAmountAttributableToParent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Redeemable common stock held by Employee Stock Ownership Plan (ESOP), $1 par value; 78,172,809 and 0 shares outstanding, recorded at redemption value</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_TemporaryEquityCarryingAmountAttributableToParent" xlink:to="us-gaap_TemporaryEquityCarryingAmountAttributableToParent_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_TemporaryEquityCarryingAmountAttributableToParent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Temporary Equity Carrying Amount Attributable To Parent</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract" xlink:type="locator" xlink:label="us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Shareholders&apos; equity (deficit)</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract" xlink:to="us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Stockholders Equity Including Portion Attributable To Noncontrolling Interest [Abstract]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CommonStockValue" xlink:type="locator" xlink:label="us-gaap_CommonStockValue" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_CommonStockValue_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Common stock, $1 par value; authorized 1,000,000,000 shares; 125,097,684 and 146,440,701 shares issued; 0 and 21,772,888; 0 and 78,896,806 shares and ESOP shares outstanding</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_CommonStockValue_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Common Stock Value</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_TreasuryStockValue" xlink:type="locator" xlink:label="us-gaap_TreasuryStockValue" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_TreasuryStockValue_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Treasury stock, 46,918,140 and 45,771,008 shares at cost</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_TreasuryStockValue" xlink:to="us-gaap_TreasuryStockValue_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_TreasuryStockValue_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Treasury Stock Value</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AdditionalPaidInCapitalCommonStock" xlink:type="locator" xlink:label="us-gaap_AdditionalPaidInCapitalCommonStock" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_AdditionalPaidInCapitalCommonStock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Additional paid-in capital</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AdditionalPaidInCapitalCommonStock" xlink:to="us-gaap_AdditionalPaidInCapitalCommonStock_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_AdditionalPaidInCapitalCommonStock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Additional Paid In Capital Common Stock</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_RetainedEarningsAccumulatedDeficit" xlink:type="locator" xlink:label="us-gaap_RetainedEarningsAccumulatedDeficit" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_RetainedEarningsAccumulatedDeficit_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Retained earnings (accumulated deficit)</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_RetainedEarningsAccumulatedDeficit" xlink:to="us-gaap_RetainedEarningsAccumulatedDeficit_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_RetainedEarningsAccumulatedDeficit_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Retained Earnings Accumulated Deficit</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax" xlink:type="locator" xlink:label="us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Accumulated other comprehensive income</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax" xlink:to="us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Accumulated Other Comprehensive Income Loss Net Of Tax</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StockholdersEquity" xlink:type="locator" xlink:label="us-gaap_StockholdersEquity" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_StockholdersEquity_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Total Parsons Corporation shareholders&apos; equity (deficit)</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_StockholdersEquity" xlink:to="us-gaap_StockholdersEquity_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_StockholdersEquity_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Stockholders Equity</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_MinorityInterest" xlink:type="locator" xlink:label="us-gaap_MinorityInterest" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_MinorityInterest_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Noncontrolling interests</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_MinorityInterest" xlink:to="us-gaap_MinorityInterest_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_MinorityInterest_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Minority Interest</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest" xlink:type="locator" xlink:label="us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Total shareholders&apos; equity (deficit)</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest" xlink:to="us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Stockholders Equity Including Portion Attributable To Noncontrolling Interest</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LiabilitiesAndStockholdersEquity" xlink:type="locator" xlink:label="us-gaap_LiabilitiesAndStockholdersEquity" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LiabilitiesAndStockholdersEquity_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Total liabilities, redeemable common stock and shareholders&apos; equity (deficit)</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LiabilitiesAndStockholdersEquity" xlink:to="us-gaap_LiabilitiesAndStockholdersEquity_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LiabilitiesAndStockholdersEquity_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Liabilities And Stockholders Equity</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementTable" xlink:type="locator" xlink:label="us-gaap_StatementTable" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_StatementTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Statement [Table]</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_StatementTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Statement [Table]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PlanNameAxis" xlink:type="locator" xlink:label="us-gaap_PlanNameAxis" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_PlanNameAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Plan Name</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_PlanNameAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Plan Name [Axis]</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_PlanNameDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Plan Name</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_PlanNameDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Plan Name [Domain]</link:label>
    <link:loc xlink:href="psn-20191231.xsd#psn_EmployeeStockOwnershipPlanMember" xlink:type="locator" xlink:label="psn_EmployeeStockOwnershipPlanMember" />
    <link:label xml:lang="en-US" xlink:label="psn_EmployeeStockOwnershipPlanMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Employee Stock Ownership Plan.</link:label>
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    <link:label xml:lang="en-US" xlink:label="psn_EmployeeStockOwnershipPlanMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Employee Stock Ownership Plan [Member]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_RelatedPartyTransactionsByRelatedPartyAxis" xlink:type="locator" xlink:label="us-gaap_RelatedPartyTransactionsByRelatedPartyAxis" />
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    <link:label xml:lang="en-US" xlink:label="us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Related Party Transactions By Related Party [Axis]</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_RelatedPartyDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Related Party</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_RelatedPartyDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Related Party [Domain]</link:label>
    <link:loc xlink:href="psn-20191231.xsd#psn_ConsolidatedJointVenturesMember" xlink:type="locator" xlink:label="psn_ConsolidatedJointVenturesMember" />
    <link:label xml:lang="en-US" xlink:label="psn_ConsolidatedJointVenturesMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Consolidated joint ventures.</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_TemporaryEquityParOrStatedValuePerShare_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Temporary equity, par value</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_TemporaryEquityParOrStatedValuePerShare" xlink:to="us-gaap_TemporaryEquityParOrStatedValuePerShare_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_TemporaryEquityParOrStatedValuePerShare_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Temporary Equity Par Or Stated Value Per Share</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_TemporaryEquitySharesOutstanding" xlink:type="locator" xlink:label="us-gaap_TemporaryEquitySharesOutstanding" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_TemporaryEquitySharesOutstanding_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Temporary equity, shares outstanding</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_TemporaryEquitySharesOutstanding" xlink:to="us-gaap_TemporaryEquitySharesOutstanding_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_TemporaryEquitySharesOutstanding_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Temporary Equity Shares Outstanding</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CommonStockParOrStatedValuePerShare" xlink:type="locator" xlink:label="us-gaap_CommonStockParOrStatedValuePerShare" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_CommonStockParOrStatedValuePerShare_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Common stock, par value</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_CommonStockParOrStatedValuePerShare" xlink:to="us-gaap_CommonStockParOrStatedValuePerShare_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_CommonStockParOrStatedValuePerShare_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Common Stock Par Or Stated Value Per Share</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CommonStockSharesAuthorized" xlink:type="locator" xlink:label="us-gaap_CommonStockSharesAuthorized" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_CommonStockSharesAuthorized_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Common stock, shares authorized</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_CommonStockSharesAuthorized" xlink:to="us-gaap_CommonStockSharesAuthorized_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_CommonStockSharesAuthorized_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Common Stock Shares Authorized</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CommonStockSharesIssued" xlink:type="locator" xlink:label="us-gaap_CommonStockSharesIssued" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_CommonStockSharesIssued_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Common stock, shares, issued</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_CommonStockSharesIssued" xlink:to="us-gaap_CommonStockSharesIssued_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_CommonStockSharesIssued_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Common Stock Shares Issued</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CommonStockSharesOutstanding" xlink:type="locator" xlink:label="us-gaap_CommonStockSharesOutstanding" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_CommonStockSharesOutstanding_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel">Common stock, shares, outstanding</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_CommonStockSharesOutstanding" xlink:to="us-gaap_CommonStockSharesOutstanding_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_CommonStockSharesOutstanding_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Common Stock Shares Outstanding</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_TreasuryStockShares" xlink:type="locator" xlink:label="us-gaap_TreasuryStockShares" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_TreasuryStockShares_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Treasury stock, shares</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_TreasuryStockShares" xlink:to="us-gaap_TreasuryStockShares_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_TreasuryStockShares_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Treasury Stock Shares</link:label>
    <link:loc xlink:href="psn-20191231.xsd#psn_GainLossOnLongTermContract" xlink:type="locator" xlink:label="psn_GainLossOnLongTermContract" />
    <link:label xml:lang="en-US" xlink:label="psn_GainLossOnLongTermContract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Gain (loss) on long-term contract.</link:label>
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    <link:loc xlink:href="psn-20191231.xsd#psn_OtherIncomeExpense" xlink:type="locator" xlink:label="psn_OtherIncomeExpense" />
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    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IncomeStatementAbstract" xlink:type="locator" xlink:label="us-gaap_IncomeStatementAbstract" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_IncomeStatementAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Income Statement [Abstract]</link:label>
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    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax" xlink:type="locator" xlink:label="us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Revenue</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax" xlink:to="us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Revenue From Contract With Customer Excluding Assessed Tax</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CostOfGoodsAndServicesSold" xlink:type="locator" xlink:label="us-gaap_CostOfGoodsAndServicesSold" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_CostOfGoodsAndServicesSold_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Direct cost of contracts</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_CostOfGoodsAndServicesSold" xlink:to="us-gaap_CostOfGoodsAndServicesSold_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_CostOfGoodsAndServicesSold_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Cost Of Goods And Services Sold</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IncomeLossFromEquityMethodInvestments" xlink:type="locator" xlink:label="us-gaap_IncomeLossFromEquityMethodInvestments" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_IncomeLossFromEquityMethodInvestments_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Equity in earnings of unconsolidated joint ventures</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_IncomeLossFromEquityMethodInvestments" xlink:to="us-gaap_IncomeLossFromEquityMethodInvestments_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_IncomeLossFromEquityMethodInvestments_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Income Loss From Equity Method Investments</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_GeneralAndAdministrativeExpense" xlink:type="locator" xlink:label="us-gaap_GeneralAndAdministrativeExpense" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_GeneralAndAdministrativeExpense_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Indirect, general and administrative expenses</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_GeneralAndAdministrativeExpense" xlink:to="us-gaap_GeneralAndAdministrativeExpense_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_GeneralAndAdministrativeExpense_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">General And Administrative Expense</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OperatingIncomeLoss" xlink:type="locator" xlink:label="us-gaap_OperatingIncomeLoss" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_OperatingIncomeLoss_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Operating income</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OperatingIncomeLoss" xlink:to="us-gaap_OperatingIncomeLoss_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_OperatingIncomeLoss_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Operating Income Loss</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_InvestmentIncomeInterest" xlink:type="locator" xlink:label="us-gaap_InvestmentIncomeInterest" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_InvestmentIncomeInterest_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Interest income</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_InvestmentIncomeInterest" xlink:to="us-gaap_InvestmentIncomeInterest_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_InvestmentIncomeInterest_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Investment Income Interest</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_InterestExpense" xlink:type="locator" xlink:label="us-gaap_InterestExpense" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_InterestExpense_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Interest expense</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_InterestExpense" xlink:to="us-gaap_InterestExpense_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_InterestExpense_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Interest Expense</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OtherNonoperatingIncomeExpense" xlink:type="locator" xlink:label="us-gaap_OtherNonoperatingIncomeExpense" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_OtherNonoperatingIncomeExpense_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Other income (expense), net</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OtherNonoperatingIncomeExpense" xlink:to="us-gaap_OtherNonoperatingIncomeExpense_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_OtherNonoperatingIncomeExpense_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Other Nonoperating Income Expense</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_GainLossOnLongTermContract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">(Interest and other expense) gain associated with claim on long-term contract</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_GainLossOnLongTermContract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Gain Loss On Long Term Contract</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_OtherIncomeExpense_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Total other (expense) income</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_OtherIncomeExpense_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Other Income Expense</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest" xlink:type="locator" xlink:label="us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Income before income tax expense</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IncomeTaxExpenseBenefit" xlink:type="locator" xlink:label="us-gaap_IncomeTaxExpenseBenefit" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_IncomeTaxExpenseBenefit_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Income tax (expense) benefit</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_IncomeTaxExpenseBenefit_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Income Tax Expense Benefit</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ProfitLoss" xlink:type="locator" xlink:label="us-gaap_ProfitLoss" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ProfitLoss_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Net income including noncontrolling interests</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ProfitLoss" xlink:to="us-gaap_ProfitLoss_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ProfitLoss_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Profit Loss</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_NetIncomeLossAttributableToNoncontrollingInterest" xlink:type="locator" xlink:label="us-gaap_NetIncomeLossAttributableToNoncontrollingInterest" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_NetIncomeLossAttributableToNoncontrollingInterest_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Net income attributable to noncontrolling interests</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_NetIncomeLossAttributableToNoncontrollingInterest_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Net Income Loss Attributable To Noncontrolling Interest</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_NetIncomeLoss" xlink:type="locator" xlink:label="us-gaap_NetIncomeLoss" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_NetIncomeLoss_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Net income attributable to Parsons Corporation</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_NetIncomeLoss" xlink:to="us-gaap_NetIncomeLoss_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_NetIncomeLoss_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Net Income Loss</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_EarningsPerShareAbstract" xlink:type="locator" xlink:label="us-gaap_EarningsPerShareAbstract" />
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    <link:label xml:lang="en-US" xlink:label="us-gaap_EarningsPerShareBasic_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Basic earnings per share</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Comprehensive income including noncontrolling interests, net of tax</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest" xlink:to="us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest" xlink:type="locator" xlink:label="us-gaap_ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Comprehensive income attributable to noncontrolling interests, net of tax</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest" xlink:to="us-gaap_ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest_lbl" />
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    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ComprehensiveIncomeNetOfTax" xlink:type="locator" xlink:label="us-gaap_ComprehensiveIncomeNetOfTax" />
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    <link:loc xlink:href="psn-20191231.xsd#psn_TemporaryEquityPurchaseOfTreasuryStock" xlink:type="locator" xlink:label="psn_TemporaryEquityPurchaseOfTreasuryStock" />
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    <link:loc xlink:href="psn-20191231.xsd#psn_TemporaryEquityContributionsOfTreasuryStockToESOP" xlink:type="locator" xlink:label="psn_TemporaryEquityContributionsOfTreasuryStockToESOP" />
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    <link:loc xlink:href="psn-20191231.xsd#psn_MinorityInterestIncreaseDecreaseFromContributionsToNoncontrollingInterestHolders" xlink:type="locator" xlink:label="psn_MinorityInterestIncreaseDecreaseFromContributionsToNoncontrollingInterestHolders" />
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    <link:loc xlink:href="psn-20191231.xsd#psn_TemporaryStockRedeemedOrCalledDuringPeriodValue" xlink:type="locator" xlink:label="psn_TemporaryStockRedeemedOrCalledDuringPeriodValue" />
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    <link:label xml:lang="en-US" xlink:label="us-gaap_EquityComponentDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Equity Component</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_EquityComponentDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Equity Component [Domain]</link:label>
    <link:loc xlink:href="psn-20191231.xsd#psn_RedeemableCommonStockMember" xlink:type="locator" xlink:label="psn_RedeemableCommonStockMember" />
    <link:label xml:lang="en-US" xlink:label="psn_RedeemableCommonStockMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Redeemable common stock.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="psn_RedeemableCommonStockMember" xlink:to="psn_RedeemableCommonStockMember_lbl" />
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    <link:label xml:lang="en-US" xlink:label="us-gaap_CommonStockMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Common Stock</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_CommonStockMember" xlink:to="us-gaap_CommonStockMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_CommonStockMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Common Stock [Member]</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_TreasuryStockMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Treasury Stock</link:label>
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    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AdditionalPaidInCapitalMember" xlink:type="locator" xlink:label="us-gaap_AdditionalPaidInCapitalMember" />
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    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ParentMember" xlink:to="us-gaap_ParentMember_lbl" />
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    <link:label xml:lang="en-US" xlink:label="us-gaap_NoncontrollingInterestMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Noncontrolling Interest</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_NoncontrollingInterestMember" xlink:to="us-gaap_NoncontrollingInterestMember_lbl" />
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    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_TypeOfAdoptionMember" xlink:to="us-gaap_TypeOfAdoptionMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_TypeOfAdoptionMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Type Of Adoption [Member]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AccountingStandardsUpdate201409Member" xlink:type="locator" xlink:label="us-gaap_AccountingStandardsUpdate201409Member" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_AccountingStandardsUpdate201409Member_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">ASC 606</link:label>
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    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AccountingStandardsUpdate201602Member" xlink:type="locator" xlink:label="us-gaap_AccountingStandardsUpdate201602Member" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_AccountingStandardsUpdate201602Member_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel">ASC 842</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AccountingStandardsUpdate201602Member" xlink:to="us-gaap_AccountingStandardsUpdate201602Member_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_AccountingStandardsUpdate201602Member_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Accounting Standards Update201602 [Member]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_SubsidiarySaleOfStockAxis" xlink:type="locator" xlink:label="us-gaap_SubsidiarySaleOfStockAxis" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_SubsidiarySaleOfStockAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Sale of Stock</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SubsidiarySaleOfStockAxis" xlink:to="us-gaap_SubsidiarySaleOfStockAxis_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_SubsidiarySaleOfStockAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Subsidiary Sale Of Stock [Axis]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_SaleOfStockNameOfTransactionDomain" xlink:type="locator" xlink:label="us-gaap_SaleOfStockNameOfTransactionDomain" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_SaleOfStockNameOfTransactionDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Sale of Stock</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SaleOfStockNameOfTransactionDomain" xlink:to="us-gaap_SaleOfStockNameOfTransactionDomain_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_SaleOfStockNameOfTransactionDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Sale Of Stock Name Of Transaction [Domain]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IPOMember" xlink:type="locator" xlink:label="us-gaap_IPOMember" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_IPOMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">IPO</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_IPOMember" xlink:to="us-gaap_IPOMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_IPOMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">I P O [Member]</link:label>
    <link:label xml:lang="en-US" xlink:label="us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/periodStartLabel">Beginning balance</link:label>
    <link:label xml:lang="en-US" xlink:label="us-gaap_TemporaryEquityCarryingAmountAttributableToParent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/periodStartLabel">Beginning balance, Temporary Equity</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterestAbstract" xlink:type="locator" xlink:label="us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterestAbstract" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterestAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Comprehensive income (loss)</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterestAbstract" xlink:to="us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterestAbstract_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterestAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest [Abstract]</link:label>
    <link:label xml:lang="en-US" xlink:label="us-gaap_ProfitLoss_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel">Net (loss) income</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationGainLossArisingDuringPeriodNetOfTax" xlink:type="locator" xlink:label="us-gaap_OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationGainLossArisingDuringPeriodNetOfTax" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationGainLossArisingDuringPeriodNetOfTax_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Foreign currency translation (loss) gain</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationGainLossArisingDuringPeriodNetOfTax" xlink:to="us-gaap_OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationGainLossArisingDuringPeriodNetOfTax_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationGainLossArisingDuringPeriodNetOfTax_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Other Comprehensive Income Foreign Currency Transaction And Translation Gain Loss Arising During Period Net Of Tax</link:label>
    <link:label xml:lang="en-US" xlink:label="us-gaap_OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Pension adjustments</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_NewAccountingPronouncementOrChangeInAccountingPrincipleEffectOfAdoptionQuantification" xlink:type="locator" xlink:label="us-gaap_NewAccountingPronouncementOrChangeInAccountingPrincipleEffectOfAdoptionQuantification" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_NewAccountingPronouncementOrChangeInAccountingPrincipleEffectOfAdoptionQuantification_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Adjustment due to adoption of ASC</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_NewAccountingPronouncementOrChangeInAccountingPrincipleEffectOfAdoptionQuantification" xlink:to="us-gaap_NewAccountingPronouncementOrChangeInAccountingPrincipleEffectOfAdoptionQuantification_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_NewAccountingPronouncementOrChangeInAccountingPrincipleEffectOfAdoptionQuantification_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">New Accounting Pronouncement Or Change In Accounting Principle Effect Of Adoption Quantification</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_TreasuryStockValueAcquiredCostMethod" xlink:type="locator" xlink:label="us-gaap_TreasuryStockValueAcquiredCostMethod" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_TreasuryStockValueAcquiredCostMethod_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Purchase of treasury stock</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_TreasuryStockValueAcquiredCostMethod" xlink:to="us-gaap_TreasuryStockValueAcquiredCostMethod_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_TreasuryStockValueAcquiredCostMethod_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Treasury Stock Value Acquired Cost Method</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_TemporaryEquityPurchaseOfTreasuryStock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Temporary equity, Purchase of treasury stock</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_TemporaryEquityPurchaseOfTreasuryStock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Temporary Equity Purchase Of Treasury Stock</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueEmployeeStockOwnershipPlan" xlink:type="locator" xlink:label="us-gaap_StockIssuedDuringPeriodValueEmployeeStockOwnershipPlan" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_StockIssuedDuringPeriodValueEmployeeStockOwnershipPlan_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Contributions of treasury stock to ESOP</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_StockIssuedDuringPeriodValueEmployeeStockOwnershipPlan" xlink:to="us-gaap_StockIssuedDuringPeriodValueEmployeeStockOwnershipPlan_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_StockIssuedDuringPeriodValueEmployeeStockOwnershipPlan_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Stock Issued During Period Value Employee Stock Ownership Plan</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_TemporaryEquityContributionsOfTreasuryStockToESOP_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Temporary equity, Contributions of treasury stock to ESOP</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_TemporaryEquityContributionsOfTreasuryStockToESOP_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Temporary Equity Contributions Of Treasury Stock To E S O P</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_MinorityInterestIncreaseDecreaseFromContributionsToNoncontrollingInterestHolders_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Contributions</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_MinorityInterestIncreaseDecreaseFromContributionsToNoncontrollingInterestHolders_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Minority Interest Increase Decrease From Contributions To Noncontrolling Interest Holders</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders" xlink:type="locator" xlink:label="us-gaap_MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Distributions</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders" xlink:to="us-gaap_MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Minority Interest Decrease From Distributions To Noncontrolling Interest Holders</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_Dividends" xlink:type="locator" xlink:label="us-gaap_Dividends" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_Dividends_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Dividend paid</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_Dividends" xlink:to="us-gaap_Dividends_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_Dividends_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Dividends</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue" xlink:type="locator" xlink:label="us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Stock-based compensation</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue" xlink:to="us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Adjustments To Additional Paid In Capital Sharebased Compensation Requisite Service Period Recognition Value</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueNewIssues" xlink:type="locator" xlink:label="us-gaap_StockIssuedDuringPeriodValueNewIssues" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_StockIssuedDuringPeriodValueNewIssues_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Issuance of equity securities, net of retirements/ IPO proceeds, net</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_StockIssuedDuringPeriodValueNewIssues" xlink:to="us-gaap_StockIssuedDuringPeriodValueNewIssues_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_StockIssuedDuringPeriodValueNewIssues_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Stock Issued During Period Value New Issues</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueConversionOfUnits" xlink:type="locator" xlink:label="us-gaap_StockIssuedDuringPeriodValueConversionOfUnits" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_StockIssuedDuringPeriodValueConversionOfUnits_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Conversion of S-Corp to C-Corp</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_StockIssuedDuringPeriodValueConversionOfUnits" xlink:to="us-gaap_StockIssuedDuringPeriodValueConversionOfUnits_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_StockIssuedDuringPeriodValueConversionOfUnits_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Stock Issued During Period Value Conversion Of Units</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_TemporaryEquityStockIssuedDuringPeriodValueConversionOfUnits_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Temporary equity, Conversion of S-Corp to C-Corp</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_TemporaryEquityStockIssuedDuringPeriodValueConversionOfUnits_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Temporary Equity Stock Issued During Period Value Conversion Of Units</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StockRedeemedOrCalledDuringPeriodValue" xlink:type="locator" xlink:label="us-gaap_StockRedeemedOrCalledDuringPeriodValue" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_StockRedeemedOrCalledDuringPeriodValue_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">ESOP shares at redemption value</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_StockRedeemedOrCalledDuringPeriodValue" xlink:to="us-gaap_StockRedeemedOrCalledDuringPeriodValue_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_StockRedeemedOrCalledDuringPeriodValue_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Stock Redeemed Or Called During Period Value</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_TemporaryStockRedeemedOrCalledDuringPeriodValue_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Temporary equity, ESOP shares at redemption value</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_TemporaryStockRedeemedOrCalledDuringPeriodValue_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Temporary Stock Redeemed Or Called During Period Value</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ReclassificationsOfTemporaryToPermanentEquity" xlink:type="locator" xlink:label="us-gaap_ReclassificationsOfTemporaryToPermanentEquity" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ReclassificationsOfTemporaryToPermanentEquity_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Temporary to permanent equity end of lock-up period</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_ReclassificationsOfTemporaryToPermanentEquity_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Reclassifications Of Temporary To Permanent Equity</link:label>
    <link:label xml:lang="en-US" xlink:label="us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/periodEndLabel">Ending Balance</link:label>
    <link:label xml:lang="en-US" xlink:label="us-gaap_TemporaryEquityCarryingAmountAttributableToParent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/periodEndLabel">Ending Balance, Temporary Equity</link:label>
    <link:loc xlink:href="psn-20191231.xsd#psn_AmortizationOfDeferredGains" xlink:type="locator" xlink:label="psn_AmortizationOfDeferredGains" />
    <link:label xml:lang="en-US" xlink:label="psn_AmortizationOfDeferredGains_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Amortization of deferred gains.</link:label>
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    <link:loc xlink:href="psn-20191231.xsd#psn_IncreaseDecreaseInPrepaidExpenseAndCurrentAssets" xlink:type="locator" xlink:label="psn_IncreaseDecreaseInPrepaidExpenseAndCurrentAssets" />
    <link:label xml:lang="en-US" xlink:label="psn_IncreaseDecreaseInPrepaidExpenseAndCurrentAssets_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Increase (decrease) in prepaid expense and current assets.</link:label>
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    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementOfCashFlowsAbstract" xlink:type="locator" xlink:label="us-gaap_StatementOfCashFlowsAbstract" />
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    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract" xlink:type="locator" xlink:label="us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Cash flows from operating activities</link:label>
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    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract" xlink:type="locator" xlink:label="us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract" />
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    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DepreciationAndAmortization" xlink:type="locator" xlink:label="us-gaap_DepreciationAndAmortization" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DepreciationAndAmortization_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Depreciation and amortization</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DepreciationAndAmortization" xlink:to="us-gaap_DepreciationAndAmortization_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DepreciationAndAmortization_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Depreciation And Amortization</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_AmortizationOfDeferredGains_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Amortization of deferred gain</link:label>
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    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AmortizationOfFinancingCosts" xlink:type="locator" xlink:label="us-gaap_AmortizationOfFinancingCosts" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_AmortizationOfFinancingCosts_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Amortization of debt issue costs</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AmortizationOfFinancingCosts" xlink:to="us-gaap_AmortizationOfFinancingCosts_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_AmortizationOfFinancingCosts_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Amortization Of Financing Costs</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_GainLossRelatedToLitigationSettlement" xlink:type="locator" xlink:label="us-gaap_GainLossRelatedToLitigationSettlement" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_GainLossRelatedToLitigationSettlement_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Gain associated with claim on long-term contract</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_GainLossRelatedToLitigationSettlement" xlink:to="us-gaap_GainLossRelatedToLitigationSettlement_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_GainLossRelatedToLitigationSettlement_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Gain Loss Related To Litigation Settlement</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_GainLossOnSaleOfPropertyPlantEquipment" xlink:type="locator" xlink:label="us-gaap_GainLossOnSaleOfPropertyPlantEquipment" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_GainLossOnSaleOfPropertyPlantEquipment_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Loss on disposal of property and equipment</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_GainLossOnSaleOfPropertyPlantEquipment" xlink:to="us-gaap_GainLossOnSaleOfPropertyPlantEquipment_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_GainLossOnSaleOfPropertyPlantEquipment_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Gain Loss On Sale Of Property Plant Equipment</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ProvisionForDoubtfulAccounts" xlink:type="locator" xlink:label="us-gaap_ProvisionForDoubtfulAccounts" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ProvisionForDoubtfulAccounts_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Provision for doubtful accounts</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ProvisionForDoubtfulAccounts" xlink:to="us-gaap_ProvisionForDoubtfulAccounts_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ProvisionForDoubtfulAccounts_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Provision For Doubtful Accounts</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DeferredIncomeTaxExpenseBenefit" xlink:type="locator" xlink:label="us-gaap_DeferredIncomeTaxExpenseBenefit" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DeferredIncomeTaxExpenseBenefit_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Deferred taxes</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DeferredIncomeTaxExpenseBenefit" xlink:to="us-gaap_DeferredIncomeTaxExpenseBenefit_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DeferredIncomeTaxExpenseBenefit_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Deferred Income Tax Expense Benefit</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ForeignCurrencyTransactionGainLossBeforeTax" xlink:type="locator" xlink:label="us-gaap_ForeignCurrencyTransactionGainLossBeforeTax" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ForeignCurrencyTransactionGainLossBeforeTax_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Foreign currency transaction gains and losses</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ForeignCurrencyTransactionGainLossBeforeTax" xlink:to="us-gaap_ForeignCurrencyTransactionGainLossBeforeTax_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ForeignCurrencyTransactionGainLossBeforeTax_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Foreign Currency Transaction Gain Loss Before Tax</link:label>
    <link:label xml:lang="en-US" xlink:label="us-gaap_IncomeLossFromEquityMethodInvestments_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Equity in earnings of unconsolidated joint ventures</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_EquityMethodInvestmentDividendsOrDistributions" xlink:type="locator" xlink:label="us-gaap_EquityMethodInvestmentDividendsOrDistributions" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_EquityMethodInvestmentDividendsOrDistributions_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Return on investments in unconsolidated joint ventures</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_EquityMethodInvestmentDividendsOrDistributions" xlink:to="us-gaap_EquityMethodInvestmentDividendsOrDistributions_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_EquityMethodInvestmentDividendsOrDistributions_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Equity Method Investment Dividends Or Distributions</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShareBasedCompensation" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensation" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensation_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Stock-based compensation</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensation" xlink:to="us-gaap_ShareBasedCompensation_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensation_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Share Based Compensation</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OtherPostretirementBenefitsExpenseReversalOfExpenseNoncash" xlink:type="locator" xlink:label="us-gaap_OtherPostretirementBenefitsExpenseReversalOfExpenseNoncash" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_OtherPostretirementBenefitsExpenseReversalOfExpenseNoncash_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Contributions of treasury stock</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OtherPostretirementBenefitsExpenseReversalOfExpenseNoncash" xlink:to="us-gaap_OtherPostretirementBenefitsExpenseReversalOfExpenseNoncash_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_OtherPostretirementBenefitsExpenseReversalOfExpenseNoncash_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Other Postretirement Benefits Expense Reversal Of Expense Noncash</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IncreaseDecreaseInOperatingCapitalAbstract" xlink:type="locator" xlink:label="us-gaap_IncreaseDecreaseInOperatingCapitalAbstract" />
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    <link:label xml:lang="en-US" xlink:label="us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Increase Decrease In Operating Capital [Abstract]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IncreaseDecreaseInAccountsReceivable" xlink:type="locator" xlink:label="us-gaap_IncreaseDecreaseInAccountsReceivable" />
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    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IncreaseDecreaseInContractWithCustomerAsset" xlink:type="locator" xlink:label="us-gaap_IncreaseDecreaseInContractWithCustomerAsset" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_IncreaseDecreaseInContractWithCustomerAsset_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Contract assets</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_IncreaseDecreaseInContractWithCustomerAsset_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Increase Decrease In Contract With Customer Asset</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_IncreaseDecreaseInPrepaidExpenseAndCurrentAssets_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Prepaid expenses and current assets</link:label>
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    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IncreaseDecreaseInAccountsPayable" xlink:type="locator" xlink:label="us-gaap_IncreaseDecreaseInAccountsPayable" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_IncreaseDecreaseInAccountsPayable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Accounts payable</link:label>
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    <link:label xml:lang="en-US" xlink:label="psn_IncreaseDecreaseInAccruedExpensesAndOtherCurrentLiabilities_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Accrued expenses and other current liabilities</link:label>
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    <link:label xml:lang="en-US" xlink:label="psn_IncreaseDecreaseInBillingsInExcessOfCosts_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Billings in excess of costs</link:label>
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    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IncreaseDecreaseInContractWithCustomerLiability" xlink:type="locator" xlink:label="us-gaap_IncreaseDecreaseInContractWithCustomerLiability" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_IncreaseDecreaseInContractWithCustomerLiability_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Contract liabilities</link:label>
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    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_EmployeeStockOwnershipPlanESOPPolicy" xlink:type="locator" xlink:label="us-gaap_EmployeeStockOwnershipPlanESOPPolicy" />
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    <link:label xml:lang="en-US" xlink:label="us-gaap_EmployeeStockOwnershipPlanESOPPolicy_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Employee Stock Ownership Plan E S O P Policy</link:label>
    <link:loc xlink:href="psn-20191231.xsd#psn_TreasuryStockPolicyPolicyTextBlock" xlink:type="locator" xlink:label="psn_TreasuryStockPolicyPolicyTextBlock" />
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    <link:loc xlink:href="psn-20191231.xsd#psn_RestrictedCashAndInvestmentsPolicyPolicyTextBlock" xlink:type="locator" xlink:label="psn_RestrictedCashAndInvestmentsPolicyPolicyTextBlock" />
    <link:label xml:lang="en-US" xlink:label="psn_RestrictedCashAndInvestmentsPolicyPolicyTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Restricted cash and investments.</link:label>
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    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ReceivablesPolicyTextBlock" xlink:type="locator" xlink:label="us-gaap_ReceivablesPolicyTextBlock" />
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    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_RevenueFromContractWithCustomerPolicyTextBlock" xlink:type="locator" xlink:label="us-gaap_RevenueFromContractWithCustomerPolicyTextBlock" />
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    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PropertyPlantAndEquipmentPolicyTextBlock" xlink:type="locator" xlink:label="us-gaap_PropertyPlantAndEquipmentPolicyTextBlock" />
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    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PropertyPlantAndEquipmentPolicyTextBlock" xlink:to="us-gaap_PropertyPlantAndEquipmentPolicyTextBlock_lbl" />
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    <link:label xml:lang="en-US" xlink:label="us-gaap_LesseeLeasesPolicyTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Leases</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_LesseeLeasesPolicyTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Lessee Leases Policy [Text Block]</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_CompensationRelatedCostsPolicyTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Compensation Related Costs Policy [Text Block]</link:label>
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    <link:loc xlink:href="psn-20191231.xsd#psn_ConsolidationOfJointVentureAndVariableInterestEntityPolicyPolicyTextBlock" xlink:type="locator" xlink:label="psn_ConsolidationOfJointVentureAndVariableInterestEntityPolicyPolicyTextBlock" />
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    <link:label xml:lang="en-US" xlink:label="us-gaap_SelfInsuranceReservePolicyTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Self Insurance Reserve Policy [Text Block]</link:label>
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    <link:label xml:lang="en-US" xlink:label="psn_PolarisAlphaMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Polaris Alpha [Member]</link:label>
    <link:loc xlink:href="psn-20191231.xsd#psn_OGSystemsMember" xlink:type="locator" xlink:label="psn_OGSystemsMember" />
    <link:label xml:lang="en-US" xlink:label="psn_OGSystemsMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">OGSystems.</link:label>
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    <link:label xml:lang="en-US" xlink:label="psn_OGSystemsMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">OGSystems</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_OGSystemsMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">O G Systems [Member]</link:label>
    <link:loc xlink:href="psn-20191231.xsd#psn_QRCTechnologiesMember" xlink:type="locator" xlink:label="psn_QRCTechnologiesMember" />
    <link:label xml:lang="en-US" xlink:label="psn_QRCTechnologiesMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">QRC Technologies.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="psn_QRCTechnologiesMember" xlink:to="psn_QRCTechnologiesMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="psn_QRCTechnologiesMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">QRC Technologies</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_QRCTechnologiesMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Q R C Technologies [Member]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ScheduleOfRecognizedIdentifiedAssetsAcquiredAndLiabilitiesAssumedTableTextBlock" xlink:type="locator" xlink:label="us-gaap_ScheduleOfRecognizedIdentifiedAssetsAcquiredAndLiabilitiesAssumedTableTextBlock" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ScheduleOfRecognizedIdentifiedAssetsAcquiredAndLiabilitiesAssumedTableTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Summary of Estimated Fair Values of Assets Acquired and Liabilities Assumed on Preliminary Purchase Price Allocation</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ScheduleOfRecognizedIdentifiedAssetsAcquiredAndLiabilitiesAssumedTableTextBlock" xlink:to="us-gaap_ScheduleOfRecognizedIdentifiedAssetsAcquiredAndLiabilitiesAssumedTableTextBlock_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ScheduleOfRecognizedIdentifiedAssetsAcquiredAndLiabilitiesAssumedTableTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Schedule Of Recognized Identified Assets Acquired And Liabilities Assumed Table [Text Block]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ScheduleOfFiniteLivedIntangibleAssetsAcquiredAsPartOfBusinessCombinationTextBlock" xlink:type="locator" xlink:label="us-gaap_ScheduleOfFiniteLivedIntangibleAssetsAcquiredAsPartOfBusinessCombinationTextBlock" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ScheduleOfFiniteLivedIntangibleAssetsAcquiredAsPartOfBusinessCombinationTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Schedule of Intangible Assets Value on Purchase Price</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ScheduleOfFiniteLivedIntangibleAssetsAcquiredAsPartOfBusinessCombinationTextBlock" xlink:to="us-gaap_ScheduleOfFiniteLivedIntangibleAssetsAcquiredAsPartOfBusinessCombinationTextBlock_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ScheduleOfFiniteLivedIntangibleAssetsAcquiredAsPartOfBusinessCombinationTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Schedule Of Finite Lived Intangible Assets Acquired As Part Of Business Combination [Text Block]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessAcquisitionProFormaInformationTextBlock" xlink:type="locator" xlink:label="us-gaap_BusinessAcquisitionProFormaInformationTextBlock" />
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    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_BusinessAcquisitionProFormaInformationTextBlock" xlink:to="us-gaap_BusinessAcquisitionProFormaInformationTextBlock_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_BusinessAcquisitionProFormaInformationTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Business Acquisition Pro Forma Information [Text Block]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DisaggregationOfRevenueTableTextBlock" xlink:type="locator" xlink:label="us-gaap_DisaggregationOfRevenueTableTextBlock" />
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    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ContractWithCustomerAssetAndLiabilityTableTextBlock" xlink:type="locator" xlink:label="us-gaap_ContractWithCustomerAssetAndLiabilityTableTextBlock" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ContractWithCustomerAssetAndLiabilityTableTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Summary of Contract Assets and Contract Liabilities</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ContractWithCustomerAssetAndLiabilityTableTextBlock" xlink:to="us-gaap_ContractWithCustomerAssetAndLiabilityTableTextBlock_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ContractWithCustomerAssetAndLiabilityTableTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Contract With Customer Asset And Liability Table [Text Block]</link:label>
    <link:loc xlink:href="psn-20191231.xsd#psn_ScheduleOfChangeInContractAssetsAndContractLiabilitiesTableTextBlock" xlink:type="locator" xlink:label="psn_ScheduleOfChangeInContractAssetsAndContractLiabilitiesTableTextBlock" />
    <link:label xml:lang="en-US" xlink:label="psn_ScheduleOfChangeInContractAssetsAndContractLiabilitiesTableTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Schedule of change in contract assets and contract liabilities.</link:label>
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    <link:label xml:lang="en-US" xlink:label="psn_ScheduleOfChangeInContractAssetsAndContractLiabilitiesTableTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Schedule of Change in Contract Assets and Contract Liabilities</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_ScheduleOfChangeInContractAssetsAndContractLiabilitiesTableTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Schedule Of Change In Contract Assets And Contract Liabilities Table [Text Block]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTextBlock" xlink:type="locator" xlink:label="us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTextBlock" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Summary of Accounts Receivable, Net</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTextBlock" xlink:to="us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTextBlock_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Schedule Of Accounts Notes Loans And Financing Receivable [Text Block]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTableTextBlock" xlink:type="locator" xlink:label="us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTableTextBlock" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTableTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Summary of Remaining Unsatisfied Performance Obligations Expect to Satisfy</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTableTextBlock" xlink:to="us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTableTextBlock_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTableTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Revenue Remaining Performance Obligation Expected Timing Of Satisfaction Table [Text Block]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LeaseCostTableTextBlock" xlink:type="locator" xlink:label="us-gaap_LeaseCostTableTextBlock" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LeaseCostTableTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Summary of Lease Costs</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LeaseCostTableTextBlock" xlink:to="us-gaap_LeaseCostTableTextBlock_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LeaseCostTableTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Lease Cost Table [Text Block]</link:label>
    <link:loc xlink:href="psn-20191231.xsd#psn_ScheduleOfCashFlowInformationRelatedToLeasesTableTextBlock" xlink:type="locator" xlink:label="psn_ScheduleOfCashFlowInformationRelatedToLeasesTableTextBlock" />
    <link:label xml:lang="en-US" xlink:label="psn_ScheduleOfCashFlowInformationRelatedToLeasesTableTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Schedule of cash flow information related to leases.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="psn_ScheduleOfCashFlowInformationRelatedToLeasesTableTextBlock" xlink:to="psn_ScheduleOfCashFlowInformationRelatedToLeasesTableTextBlock_lbl" />
    <link:label xml:lang="en-US" xlink:label="psn_ScheduleOfCashFlowInformationRelatedToLeasesTableTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Schedule of Supplemental Cash Flow Information Related to Leases</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_ScheduleOfCashFlowInformationRelatedToLeasesTableTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Schedule Of Cash Flow Information Related To Leases Table [Text Block]</link:label>
    <link:loc xlink:href="psn-20191231.xsd#psn_ScheduleOfBalanceSheetInformationRelatedToLeasesTableTextBlock" xlink:type="locator" xlink:label="psn_ScheduleOfBalanceSheetInformationRelatedToLeasesTableTextBlock" />
    <link:label xml:lang="en-US" xlink:label="psn_ScheduleOfBalanceSheetInformationRelatedToLeasesTableTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Schedule of balance sheet information related to leases.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="psn_ScheduleOfBalanceSheetInformationRelatedToLeasesTableTextBlock" xlink:to="psn_ScheduleOfBalanceSheetInformationRelatedToLeasesTableTextBlock_lbl" />
    <link:label xml:lang="en-US" xlink:label="psn_ScheduleOfBalanceSheetInformationRelatedToLeasesTableTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Schedule of Supplemental Balance Sheet and Other Information Related to Leases</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_ScheduleOfBalanceSheetInformationRelatedToLeasesTableTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Schedule Of Balance Sheet Information Related To Leases Table [Text Block]</link:label>
    <link:loc xlink:href="psn-20191231.xsd#psn_ScheduleOfMaturitiesOfOperatingAndFinanceLeaseLiabilitiesTableTextBlock" xlink:type="locator" xlink:label="psn_ScheduleOfMaturitiesOfOperatingAndFinanceLeaseLiabilitiesTableTextBlock" />
    <link:label xml:lang="en-US" xlink:label="psn_ScheduleOfMaturitiesOfOperatingAndFinanceLeaseLiabilitiesTableTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Schedule of maturities of operating and finance lease liabilities.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="psn_ScheduleOfMaturitiesOfOperatingAndFinanceLeaseLiabilitiesTableTextBlock" xlink:to="psn_ScheduleOfMaturitiesOfOperatingAndFinanceLeaseLiabilitiesTableTextBlock_lbl" />
    <link:label xml:lang="en-US" xlink:label="psn_ScheduleOfMaturitiesOfOperatingAndFinanceLeaseLiabilitiesTableTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Schedule of Maturity Analysis of Future Undiscounted Cash Flows</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_ScheduleOfMaturitiesOfOperatingAndFinanceLeaseLiabilitiesTableTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Schedule Of Maturities Of Operating And Finance Lease Liabilities Table [Text Block]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AwardTypeAxis" xlink:type="locator" xlink:label="us-gaap_AwardTypeAxis" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_AwardTypeAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Award Type</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_AwardTypeAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Award Type [Axis]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Award Type</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Share Based Compensation Arrangements By Share Based Payment Award Award Type And Plan Name [Domain]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StockAppreciationRightsSARSMember" xlink:type="locator" xlink:label="us-gaap_StockAppreciationRightsSARSMember" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_StockAppreciationRightsSARSMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Stock Appreciation Rights</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_StockAppreciationRightsSARSMember" xlink:to="us-gaap_StockAppreciationRightsSARSMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_StockAppreciationRightsSARSMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Stock Appreciation Rights S A R S [Member]</link:label>
    <link:loc xlink:href="psn-20191231.xsd#psn_LongTermGrowthUnitsMember" xlink:type="locator" xlink:label="psn_LongTermGrowthUnitsMember" />
    <link:label xml:lang="en-US" xlink:label="psn_LongTermGrowthUnitsMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Long-term growth units.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="psn_LongTermGrowthUnitsMember" xlink:to="psn_LongTermGrowthUnitsMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="psn_LongTermGrowthUnitsMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Long-Term Growth Units</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_LongTermGrowthUnitsMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Long Term Growth Units [Member]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_RestrictedStockMember" xlink:type="locator" xlink:label="us-gaap_RestrictedStockMember" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_RestrictedStockMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Restricted Award Units</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_RestrictedStockMember" xlink:to="us-gaap_RestrictedStockMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_RestrictedStockMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Restricted Stock [Member]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_RestrictedStockUnitsRSUMember" xlink:type="locator" xlink:label="us-gaap_RestrictedStockUnitsRSUMember" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_RestrictedStockUnitsRSUMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Restricted Stock Units</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_RestrictedStockUnitsRSUMember" xlink:to="us-gaap_RestrictedStockUnitsRSUMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_RestrictedStockUnitsRSUMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Restricted Stock Units R S U [Member]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ScheduleOfShareBasedPaymentAwardStockOptionsValuationAssumptionsTableTextBlock" xlink:type="locator" xlink:label="us-gaap_ScheduleOfShareBasedPaymentAwardStockOptionsValuationAssumptionsTableTextBlock" />
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    <link:label xml:lang="en-US" xlink:label="us-gaap_ScheduleOfShareBasedCompensationStockAppreciationRightsAwardActivityTableTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Summary of Stock Appreciation Right Activity</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ScheduleOfShareBasedCompensationStockAppreciationRightsAwardActivityTableTextBlock" xlink:to="us-gaap_ScheduleOfShareBasedCompensationStockAppreciationRightsAwardActivityTableTextBlock_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ScheduleOfShareBasedCompensationStockAppreciationRightsAwardActivityTableTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Schedule Of Share Based Compensation Stock Appreciation Rights Award Activity Table [Text Block]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ScheduleOfNonvestedShareActivityTableTextBlock" xlink:type="locator" xlink:label="us-gaap_ScheduleOfNonvestedShareActivityTableTextBlock" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ScheduleOfNonvestedShareActivityTableTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Schedule of Unvested Share Activity</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ScheduleOfNonvestedShareActivityTableTextBlock" xlink:to="us-gaap_ScheduleOfNonvestedShareActivityTableTextBlock_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ScheduleOfNonvestedShareActivityTableTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Schedule Of Nonvested Share Activity Table [Text Block]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationRestrictedStockUnitsAwardActivityTableTextBlock" xlink:type="locator" xlink:label="us-gaap_ScheduleOfShareBasedCompensationRestrictedStockUnitsAwardActivityTableTextBlock" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ScheduleOfShareBasedCompensationRestrictedStockUnitsAwardActivityTableTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Summary of Restricted Stock Unit Activity</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ScheduleOfShareBasedCompensationRestrictedStockUnitsAwardActivityTableTextBlock" xlink:to="us-gaap_ScheduleOfShareBasedCompensationRestrictedStockUnitsAwardActivityTableTextBlock_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ScheduleOfShareBasedCompensationRestrictedStockUnitsAwardActivityTableTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Schedule Of Share Based Compensation Restricted Stock Units Award Activity Table [Text Block]</link:label>
    <link:loc xlink:href="psn-20191231.xsd#psn_ScheduleOfAmountPaidForCashSettledAwardsTableTextBlock" xlink:type="locator" xlink:label="psn_ScheduleOfAmountPaidForCashSettledAwardsTableTextBlock" />
    <link:label xml:lang="en-US" xlink:label="psn_ScheduleOfAmountPaidForCashSettledAwardsTableTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Schedule of amount paid for cash settled awards.</link:label>
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    <link:label xml:lang="en-US" xlink:label="psn_ScheduleOfAmountPaidForCashSettledAwardsTableTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Schedule of Amount Paid for Cash Settled Awards by Award Type</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_ScheduleOfAmountPaidForCashSettledAwardsTableTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Schedule Of Amount Paid For Cash Settled Awards Table [Text Block]</link:label>
    <link:loc xlink:href="psn-20191231.xsd#psn_ScheduleOfShareBasedCompensationRestrictedStockOutstandingActivityTableTextBlock" xlink:type="locator" xlink:label="psn_ScheduleOfShareBasedCompensationRestrictedStockOutstandingActivityTableTextBlock" />
    <link:label xml:lang="en-US" xlink:label="psn_ScheduleOfShareBasedCompensationRestrictedStockOutstandingActivityTableTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Schedule of share based compensation restricted stock outstanding activity.</link:label>
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    <link:label xml:lang="en-US" xlink:label="psn_ScheduleOfShareBasedCompensationRestrictedStockOutstandingActivityTableTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Summary of Restricted Stock Outstanding</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_ScheduleOfShareBasedCompensationRestrictedStockOutstandingActivityTableTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Schedule Of Share Based Compensation Restricted Stock Outstanding Activity Table [Text Block]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ScheduleOfGoodwillTextBlock" xlink:type="locator" xlink:label="us-gaap_ScheduleOfGoodwillTextBlock" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ScheduleOfGoodwillTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Summary of Changes in Carrying Value of Goodwill by Reporting Segment</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ScheduleOfGoodwillTextBlock" xlink:to="us-gaap_ScheduleOfGoodwillTextBlock_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ScheduleOfGoodwillTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Schedule Of Goodwill [Text Block]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ScheduleOfAcquiredFiniteLivedIntangibleAssetsByMajorClassTextBlock" xlink:type="locator" xlink:label="us-gaap_ScheduleOfAcquiredFiniteLivedIntangibleAssetsByMajorClassTextBlock" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ScheduleOfAcquiredFiniteLivedIntangibleAssetsByMajorClassTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Schedule of Gross Amount and Accumulated Amortization of Intangible Assets</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ScheduleOfAcquiredFiniteLivedIntangibleAssetsByMajorClassTextBlock" xlink:to="us-gaap_ScheduleOfAcquiredFiniteLivedIntangibleAssetsByMajorClassTextBlock_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ScheduleOfAcquiredFiniteLivedIntangibleAssetsByMajorClassTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Schedule Of Acquired Finite Lived Intangible Assets By Major Class [Text Block]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ScheduleofFiniteLivedIntangibleAssetsFutureAmortizationExpenseTableTextBlock" xlink:type="locator" xlink:label="us-gaap_ScheduleofFiniteLivedIntangibleAssetsFutureAmortizationExpenseTableTextBlock" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ScheduleofFiniteLivedIntangibleAssetsFutureAmortizationExpenseTableTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Schedule of Estimated Amortization Expense</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ScheduleofFiniteLivedIntangibleAssetsFutureAmortizationExpenseTableTextBlock" xlink:to="us-gaap_ScheduleofFiniteLivedIntangibleAssetsFutureAmortizationExpenseTableTextBlock_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ScheduleofFiniteLivedIntangibleAssetsFutureAmortizationExpenseTableTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Scheduleof Finite Lived Intangible Assets Future Amortization Expense Table [Text Block]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PropertyPlantAndEquipmentTextBlock" xlink:type="locator" xlink:label="us-gaap_PropertyPlantAndEquipmentTextBlock" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_PropertyPlantAndEquipmentTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Schedule of Property and equipment, net</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PropertyPlantAndEquipmentTextBlock" xlink:to="us-gaap_PropertyPlantAndEquipmentTextBlock_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_PropertyPlantAndEquipmentTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Property Plant And Equipment [Text Block]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ScheduleOfAccountsPayableAndAccruedLiabilitiesTableTextBlock" xlink:type="locator" xlink:label="us-gaap_ScheduleOfAccountsPayableAndAccruedLiabilitiesTableTextBlock" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ScheduleOfAccountsPayableAndAccruedLiabilitiesTableTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Schedule of Accrued Expenses and Other Current Liabilities</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ScheduleOfAccountsPayableAndAccruedLiabilitiesTableTextBlock" xlink:to="us-gaap_ScheduleOfAccountsPayableAndAccruedLiabilitiesTableTextBlock_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ScheduleOfAccountsPayableAndAccruedLiabilitiesTableTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Schedule Of Accounts Payable And Accrued Liabilities Table [Text Block]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ScheduleOfDebtTableTextBlock" xlink:type="locator" xlink:label="us-gaap_ScheduleOfDebtTableTextBlock" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ScheduleOfDebtTableTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Schedule of Long Term Debt</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ScheduleOfDebtTableTextBlock" xlink:to="us-gaap_ScheduleOfDebtTableTextBlock_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ScheduleOfDebtTableTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Schedule Of Debt Table [Text Block]</link:label>
    <link:loc xlink:href="psn-20191231.xsd#psn_ScheduleOfAggregateAmountDebtRepayableTableTextBlock" xlink:type="locator" xlink:label="psn_ScheduleOfAggregateAmountDebtRepayableTableTextBlock" />
    <link:label xml:lang="en-US" xlink:label="psn_ScheduleOfAggregateAmountDebtRepayableTableTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Schedule of aggregate amount debt repayable.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="psn_ScheduleOfAggregateAmountDebtRepayableTableTextBlock" xlink:to="psn_ScheduleOfAggregateAmountDebtRepayableTableTextBlock_lbl" />
    <link:label xml:lang="en-US" xlink:label="psn_ScheduleOfAggregateAmountDebtRepayableTableTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Schedule of Aggregate Amount Debt Repayable</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_ScheduleOfAggregateAmountDebtRepayableTableTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Schedule Of Aggregate Amount Debt Repayable Table [Text Block]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OtherNoncurrentLiabilitiesTableTextBlock" xlink:type="locator" xlink:label="us-gaap_OtherNoncurrentLiabilitiesTableTextBlock" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_OtherNoncurrentLiabilitiesTableTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Schedule of Other Long-term Liabilities</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OtherNoncurrentLiabilitiesTableTextBlock" xlink:to="us-gaap_OtherNoncurrentLiabilitiesTableTextBlock_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_OtherNoncurrentLiabilitiesTableTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Other Noncurrent Liabilities Table [Text Block]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ScheduleOfIncomeBeforeIncomeTaxDomesticAndForeignTableTextBlock" xlink:type="locator" xlink:label="us-gaap_ScheduleOfIncomeBeforeIncomeTaxDomesticAndForeignTableTextBlock" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ScheduleOfIncomeBeforeIncomeTaxDomesticAndForeignTableTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Components of Income from Continuing Operations Before Income Taxes</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ScheduleOfIncomeBeforeIncomeTaxDomesticAndForeignTableTextBlock" xlink:to="us-gaap_ScheduleOfIncomeBeforeIncomeTaxDomesticAndForeignTableTextBlock_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ScheduleOfIncomeBeforeIncomeTaxDomesticAndForeignTableTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Schedule Of Income Before Income Tax Domestic And Foreign Table [Text Block]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ScheduleOfComponentsOfIncomeTaxExpenseBenefitTableTextBlock" xlink:type="locator" xlink:label="us-gaap_ScheduleOfComponentsOfIncomeTaxExpenseBenefitTableTextBlock" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ScheduleOfComponentsOfIncomeTaxExpenseBenefitTableTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Schedule of Income Tax Expense (Benefit) Attributable to Income from Continuing Operations</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ScheduleOfComponentsOfIncomeTaxExpenseBenefitTableTextBlock" xlink:to="us-gaap_ScheduleOfComponentsOfIncomeTaxExpenseBenefitTableTextBlock_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ScheduleOfComponentsOfIncomeTaxExpenseBenefitTableTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Schedule Of Components Of Income Tax Expense Benefit Table [Text Block]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ScheduleOfEffectiveIncomeTaxRateReconciliationTableTextBlock" xlink:type="locator" xlink:label="us-gaap_ScheduleOfEffectiveIncomeTaxRateReconciliationTableTextBlock" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ScheduleOfEffectiveIncomeTaxRateReconciliationTableTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Computation of Income Tax Expense (Benefit)</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_ScheduleOfEffectiveIncomeTaxRateReconciliationTableTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Schedule Of Effective Income Tax Rate Reconciliation Table [Text Block]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ScheduleOfDeferredTaxAssetsAndLiabilitiesTableTextBlock" xlink:type="locator" xlink:label="us-gaap_ScheduleOfDeferredTaxAssetsAndLiabilitiesTableTextBlock" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ScheduleOfDeferredTaxAssetsAndLiabilitiesTableTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Components of Deferred Tax Assets and Liabilities</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ScheduleOfDeferredTaxAssetsAndLiabilitiesTableTextBlock" xlink:to="us-gaap_ScheduleOfDeferredTaxAssetsAndLiabilitiesTableTextBlock_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ScheduleOfDeferredTaxAssetsAndLiabilitiesTableTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Schedule Of Deferred Tax Assets And Liabilities Table [Text Block]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ScheduleOfUnrecognizedTaxBenefitsRollForwardTableTextBlock" xlink:type="locator" xlink:label="us-gaap_ScheduleOfUnrecognizedTaxBenefitsRollForwardTableTextBlock" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ScheduleOfUnrecognizedTaxBenefitsRollForwardTableTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Reconciliation of Beginning and Ending Balances of Unrecognized Tax Benefits</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_ScheduleOfUnrecognizedTaxBenefitsRollForwardTableTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Schedule Of Unrecognized Tax Benefits Roll Forward Table [Text Block]</link:label>
    <link:loc xlink:href="psn-20191231.xsd#psn_ScheduleOfFinancialInformationOfConsolidatedJointVenturesTableTextBlock" xlink:type="locator" xlink:label="psn_ScheduleOfFinancialInformationOfConsolidatedJointVenturesTableTextBlock" />
    <link:label xml:lang="en-US" xlink:label="psn_ScheduleOfFinancialInformationOfConsolidatedJointVenturesTableTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Schedule of financial information of consolidated joint ventures.</link:label>
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    <link:label xml:lang="en-US" xlink:label="psn_ScheduleOfFinancialInformationOfConsolidatedJointVenturesTableTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Schedule of Financial Information of Consolidated Joint Ventures</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_ScheduleOfFinancialInformationOfConsolidatedJointVenturesTableTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Schedule Of Financial Information Of Consolidated Joint Ventures Table [Text Block]</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_EquityMethodInvestmentsTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Equity Method Investments [Text Block]</link:label>
    <link:loc xlink:href="psn-20191231.xsd#psn_ScheduleOfConsolidatedBalanceSheetRelatedToUnconsolidatedJointVenturesTableTextBlock" xlink:type="locator" xlink:label="psn_ScheduleOfConsolidatedBalanceSheetRelatedToUnconsolidatedJointVenturesTableTextBlock" />
    <link:label xml:lang="en-US" xlink:label="psn_ScheduleOfConsolidatedBalanceSheetRelatedToUnconsolidatedJointVenturesTableTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Schedule of consolidated balance sheet related to unconsolidated joint ventures.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="psn_ScheduleOfConsolidatedBalanceSheetRelatedToUnconsolidatedJointVenturesTableTextBlock" xlink:to="psn_ScheduleOfConsolidatedBalanceSheetRelatedToUnconsolidatedJointVenturesTableTextBlock_lbl" />
    <link:label xml:lang="en-US" xlink:label="psn_ScheduleOfConsolidatedBalanceSheetRelatedToUnconsolidatedJointVenturesTableTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Schedule of Consolidated Balance Sheet Related to Services Provided to Unconsolidated Joint Ventures</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_ScheduleOfConsolidatedBalanceSheetRelatedToUnconsolidatedJointVenturesTableTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Schedule Of Consolidated Balance Sheet Related To Unconsolidated Joint Ventures Table [Text Block]</link:label>
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    <link:label xml:lang="en-US" xlink:label="psn_SummaryOfFairValueAssetsAssociatedWithPensionPlanTableTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Summary of Fair Value Assets Associated with Pension Plan</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_SummaryOfFairValueAssetsAssociatedWithPensionPlanTableTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Summary Of Fair Value Assets Associated With Pension Plan Table [Text Block]</link:label>
    <link:loc xlink:href="psn-20191231.xsd#psn_ScheduleOfFairValueOfRedeemableCommonStockAssociatedEmployeeStockOwnershipPlanTableTextBlock" xlink:type="locator" xlink:label="psn_ScheduleOfFairValueOfRedeemableCommonStockAssociatedEmployeeStockOwnershipPlanTableTextBlock" />
    <link:label xml:lang="en-US" xlink:label="psn_ScheduleOfFairValueOfRedeemableCommonStockAssociatedEmployeeStockOwnershipPlanTableTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Schedule of fair value of redeemable common stock associated employee stock ownership plan.</link:label>
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    <link:label xml:lang="en-US" xlink:label="psn_ScheduleOfFairValueOfRedeemableCommonStockAssociatedEmployeeStockOwnershipPlanTableTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Schedule of Fair Value of Redeemable Common Stock Associated Employee Stock Ownership Plan</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_ScheduleOfFairValueOfRedeemableCommonStockAssociatedEmployeeStockOwnershipPlanTableTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Schedule Of Fair Value Of Redeemable Common Stock Associated Employee Stock Ownership Plan Table [Text Block]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationTextBlock" xlink:type="locator" xlink:label="us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationTextBlock" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Schedule of Reconciliation Fair Value Measurements Using Significant Unobservable Inputs</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationTextBlock" xlink:to="us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationTextBlock_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Text Block]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ScheduleOfWeightedAverageNumberOfSharesTableTextBlock" xlink:type="locator" xlink:label="us-gaap_ScheduleOfWeightedAverageNumberOfSharesTableTextBlock" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ScheduleOfWeightedAverageNumberOfSharesTableTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Schedule of Weighted Average Number of Shares Used To Compute Basic and Diluted EPS</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ScheduleOfWeightedAverageNumberOfSharesTableTextBlock" xlink:to="us-gaap_ScheduleOfWeightedAverageNumberOfSharesTableTextBlock_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ScheduleOfWeightedAverageNumberOfSharesTableTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Schedule Of Weighted Average Number Of Shares Table [Text Block]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTextBlock" xlink:type="locator" xlink:label="us-gaap_ScheduleOfSegmentReportingInformationBySegmentTextBlock" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ScheduleOfSegmentReportingInformationBySegmentTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Summary of Business Segment Information</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ScheduleOfSegmentReportingInformationBySegmentTextBlock" xlink:to="us-gaap_ScheduleOfSegmentReportingInformationBySegmentTextBlock_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ScheduleOfSegmentReportingInformationBySegmentTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Schedule Of Segment Reporting Information By Segment [Text Block]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ReconciliationOfOperatingProfitLossFromSegmentsToConsolidatedTextBlock" xlink:type="locator" xlink:label="us-gaap_ReconciliationOfOperatingProfitLossFromSegmentsToConsolidatedTextBlock" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ReconciliationOfOperatingProfitLossFromSegmentsToConsolidatedTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Summary of Adjusted EBITDA Business Segment Information</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ReconciliationOfOperatingProfitLossFromSegmentsToConsolidatedTextBlock" xlink:to="us-gaap_ReconciliationOfOperatingProfitLossFromSegmentsToConsolidatedTextBlock_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ReconciliationOfOperatingProfitLossFromSegmentsToConsolidatedTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Reconciliation Of Operating Profit Loss From Segments To Consolidated [Text Block]</link:label>
    <link:loc xlink:href="psn-20191231.xsd#psn_SummaryOfRevenuesAndPropertyAndEquipmentNetByGeographicAreaTableTextBlock" xlink:type="locator" xlink:label="psn_SummaryOfRevenuesAndPropertyAndEquipmentNetByGeographicAreaTableTextBlock" />
    <link:label xml:lang="en-US" xlink:label="psn_SummaryOfRevenuesAndPropertyAndEquipmentNetByGeographicAreaTableTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Summary of revenues and property and equipment, net by geographic area.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="psn_SummaryOfRevenuesAndPropertyAndEquipmentNetByGeographicAreaTableTextBlock" xlink:to="psn_SummaryOfRevenuesAndPropertyAndEquipmentNetByGeographicAreaTableTextBlock_lbl" />
    <link:label xml:lang="en-US" xlink:label="psn_SummaryOfRevenuesAndPropertyAndEquipmentNetByGeographicAreaTableTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Summary of Revenues and Property and Equipment, Net by Geographic Area</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_SummaryOfRevenuesAndPropertyAndEquipmentNetByGeographicAreaTableTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Summary Of Revenues And Property And Equipment Net By Geographic Area Table [Text Block]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ScheduleOfEntityWideInformationRevenueFromExternalCustomersByProductsAndServicesTextBlock" xlink:type="locator" xlink:label="us-gaap_ScheduleOfEntityWideInformationRevenueFromExternalCustomersByProductsAndServicesTextBlock" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ScheduleOfEntityWideInformationRevenueFromExternalCustomersByProductsAndServicesTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Summary of Revenues by Business Lines</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ScheduleOfEntityWideInformationRevenueFromExternalCustomersByProductsAndServicesTextBlock" xlink:to="us-gaap_ScheduleOfEntityWideInformationRevenueFromExternalCustomersByProductsAndServicesTextBlock_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ScheduleOfEntityWideInformationRevenueFromExternalCustomersByProductsAndServicesTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Schedule Of Entity Wide Information Revenue From External Customers By Products And Services [Text Block]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ScheduleOfQuarterlyFinancialInformationTableTextBlock" xlink:type="locator" xlink:label="us-gaap_ScheduleOfQuarterlyFinancialInformationTableTextBlock" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ScheduleOfQuarterlyFinancialInformationTableTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Schedule of Selected Quarterly Financial Information</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ScheduleOfQuarterlyFinancialInformationTableTextBlock" xlink:to="us-gaap_ScheduleOfQuarterlyFinancialInformationTableTextBlock_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ScheduleOfQuarterlyFinancialInformationTableTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Schedule Of Quarterly Financial Information Table [Text Block]</link:label>
    <link:loc xlink:href="psn-20191231.xsd#psn_PurchaseOfAdditionalSharesUponExerciseOfOptions" xlink:type="locator" xlink:label="psn_PurchaseOfAdditionalSharesUponExerciseOfOptions" />
    <link:label xml:lang="en-US" xlink:label="psn_PurchaseOfAdditionalSharesUponExerciseOfOptions_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Purchase of additional shares upon exercise of options.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="psn_PurchaseOfAdditionalSharesUponExerciseOfOptions" xlink:to="psn_PurchaseOfAdditionalSharesUponExerciseOfOptions_lbl" />
    <link:loc xlink:href="psn-20191231.xsd#psn_UnderwritingDiscountPerShare" xlink:type="locator" xlink:label="psn_UnderwritingDiscountPerShare" />
    <link:label xml:lang="en-US" xlink:label="psn_UnderwritingDiscountPerShare_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Underwriting discount per share.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="psn_UnderwritingDiscountPerShare" xlink:to="psn_UnderwritingDiscountPerShare_lbl" />
    <link:loc xlink:href="psn-20191231.xsd#psn_FundsToDividendsThroughPublicOffering" xlink:type="locator" xlink:label="psn_FundsToDividendsThroughPublicOffering" />
    <link:label xml:lang="en-US" xlink:label="psn_FundsToDividendsThroughPublicOffering_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Funds to dividends through public offering.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="psn_FundsToDividendsThroughPublicOffering" xlink:to="psn_FundsToDividendsThroughPublicOffering_lbl" />
    <link:loc xlink:href="psn-20191231.xsd#psn_RepaymentOnTermLoanThroughPublicOffering" xlink:type="locator" xlink:label="psn_RepaymentOnTermLoanThroughPublicOffering" />
    <link:label xml:lang="en-US" xlink:label="psn_RepaymentOnTermLoanThroughPublicOffering_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Repayment on term loan through public offering.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="psn_RepaymentOnTermLoanThroughPublicOffering" xlink:to="psn_RepaymentOnTermLoanThroughPublicOffering_lbl" />
    <link:loc xlink:href="psn-20191231.xsd#psn_DescriptionOfOperationsDisclosureLineItems" xlink:type="locator" xlink:label="psn_DescriptionOfOperationsDisclosureLineItems" />
    <link:label xml:lang="en-US" xlink:label="psn_DescriptionOfOperationsDisclosureLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Description of operations disclosure.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="psn_DescriptionOfOperationsDisclosureLineItems" xlink:to="psn_DescriptionOfOperationsDisclosureLineItems_lbl" />
    <link:loc xlink:href="psn-20191231.xsd#psn_DescriptionOfOperationsDisclosureTable" xlink:type="locator" xlink:label="psn_DescriptionOfOperationsDisclosureTable" />
    <link:label xml:lang="en-US" xlink:label="psn_DescriptionOfOperationsDisclosureTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Description of operations disclosure.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="psn_DescriptionOfOperationsDisclosureTable" xlink:to="psn_DescriptionOfOperationsDisclosureTable_lbl" />
    <link:label xml:lang="en-US" xlink:label="psn_DescriptionOfOperationsDisclosureTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Description Of Operations Disclosure [Table]</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_DescriptionOfOperationsDisclosureTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Description Of Operations Disclosure [Table]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OverAllotmentOptionMember" xlink:type="locator" xlink:label="us-gaap_OverAllotmentOptionMember" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_OverAllotmentOptionMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Underwriters</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OverAllotmentOptionMember" xlink:to="us-gaap_OverAllotmentOptionMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_OverAllotmentOptionMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Over Allotment Option [Member]</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_DescriptionOfOperationsDisclosureLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Description Of Operations Disclosure [Line Items]</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_DescriptionOfOperationsDisclosureLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Description Of Operations Disclosure [Line Items]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesNewIssues" xlink:type="locator" xlink:label="us-gaap_StockIssuedDuringPeriodSharesNewIssues" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_StockIssuedDuringPeriodSharesNewIssues_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Common stock shares sold</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_StockIssuedDuringPeriodSharesNewIssues" xlink:to="us-gaap_StockIssuedDuringPeriodSharesNewIssues_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_StockIssuedDuringPeriodSharesNewIssues_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Stock Issued During Period Shares New Issues</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_SaleOfStockPricePerShare" xlink:type="locator" xlink:label="us-gaap_SaleOfStockPricePerShare" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_SaleOfStockPricePerShare_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Common stock sold per share</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SaleOfStockPricePerShare" xlink:to="us-gaap_SaleOfStockPricePerShare_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_SaleOfStockPricePerShare_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Sale Of Stock Price Per Share</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_PurchaseOfAdditionalSharesUponExerciseOfOptions_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Purchase of additional shares upon exercise of options</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_PurchaseOfAdditionalSharesUponExerciseOfOptions_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Purchase Of Additional Shares Upon Exercise Of Options</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_SharePrice" xlink:type="locator" xlink:label="us-gaap_SharePrice" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_SharePrice_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Share price</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SharePrice" xlink:to="us-gaap_SharePrice_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_SharePrice_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Share Price</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_UnderwritingDiscountPerShare_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Underwriting discount per share</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_UnderwritingDiscountPerShare_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Underwriting Discount Per Share</link:label>
    <link:label xml:lang="en-US" xlink:label="us-gaap_ProceedsFromIssuanceInitialPublicOffering_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Proceeds from IPO</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_FundsToDividendsThroughPublicOffering_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Funds to dividend through public offering</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_FundsToDividendsThroughPublicOffering_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Funds To Dividends Through Public Offering</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_RepaymentOnTermLoanThroughPublicOffering_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Repayment on term loan through public offering</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_RepaymentOnTermLoanThroughPublicOffering_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Repayment On Term Loan Through Public Offering</link:label>
    <link:loc xlink:href="psn-20191231.xsd#psn_CommonStockDividendRatio" xlink:type="locator" xlink:label="psn_CommonStockDividendRatio" />
    <link:label xml:lang="en-US" xlink:label="psn_CommonStockDividendRatio_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Common stock dividend ratio.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="psn_CommonStockDividendRatio" xlink:to="psn_CommonStockDividendRatio_lbl" />
    <link:loc xlink:href="psn-20191231.xsd#psn_DividendPayablePaymentDate" xlink:type="locator" xlink:label="psn_DividendPayablePaymentDate" />
    <link:label xml:lang="en-US" xlink:label="psn_DividendPayablePaymentDate_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Dividend payable payment date.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="psn_DividendPayablePaymentDate" xlink:to="psn_DividendPayablePaymentDate_lbl" />
    <link:label xml:lang="en-US" xlink:label="psn_CommonStockDividendRatio_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Common stock dividend ratio</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_CommonStockDividendRatio_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Common Stock Dividend Ratio</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DividendsPayableDateDeclaredDayMonthAndYear" xlink:type="locator" xlink:label="us-gaap_DividendsPayableDateDeclaredDayMonthAndYear" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DividendsPayableDateDeclaredDayMonthAndYear_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Dividends declared date</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DividendsPayableDateDeclaredDayMonthAndYear" xlink:to="us-gaap_DividendsPayableDateDeclaredDayMonthAndYear_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DividendsPayableDateDeclaredDayMonthAndYear_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Dividends Payable Date Declared Day Month And Year</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_DividendPayablePaymentDate_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Dividends payment, date</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_DividendPayablePaymentDate_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Dividend Payable Payment Date</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DividendsPayableDateOfRecordDayMonthAndYear" xlink:type="locator" xlink:label="us-gaap_DividendsPayableDateOfRecordDayMonthAndYear" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DividendsPayableDateOfRecordDayMonthAndYear_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Dividends record date</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DividendsPayableDateOfRecordDayMonthAndYear" xlink:to="us-gaap_DividendsPayableDateOfRecordDayMonthAndYear_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DividendsPayableDateOfRecordDayMonthAndYear_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Dividends Payable Date Of Record Day Month And Year</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AccountingPoliciesAbstract" xlink:type="locator" xlink:label="us-gaap_AccountingPoliciesAbstract" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_AccountingPoliciesAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Accounting Policies [Abstract]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AccountingPoliciesAbstract" xlink:to="us-gaap_AccountingPoliciesAbstract_lbl" />
    <link:loc xlink:href="psn-20191231.xsd#psn_SignificantAccountingPoliciesLineItems" xlink:type="locator" xlink:label="psn_SignificantAccountingPoliciesLineItems" />
    <link:label xml:lang="en-US" xlink:label="psn_SignificantAccountingPoliciesLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Significant Accounting Policies [Line Items]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="psn_SignificantAccountingPoliciesLineItems" xlink:to="psn_SignificantAccountingPoliciesLineItems_lbl" />
    <link:loc xlink:href="psn-20191231.xsd#psn_SignificantAccountingPoliciesTable" xlink:type="locator" xlink:label="psn_SignificantAccountingPoliciesTable" />
    <link:label xml:lang="en-US" xlink:label="psn_SignificantAccountingPoliciesTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Significant Accounting Policies [Table]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="psn_SignificantAccountingPoliciesTable" xlink:to="psn_SignificantAccountingPoliciesTable_lbl" />
    <link:label xml:lang="en-US" xlink:label="psn_SignificantAccountingPoliciesTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Significant Accounting Policies [Table]</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_SignificantAccountingPoliciesTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Significant Accounting Policies [Table]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_RangeAxis" xlink:type="locator" xlink:label="srt_RangeAxis" />
    <link:label xml:lang="en-US" xlink:label="srt_RangeAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Statistical Measurement</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="srt_RangeAxis" xlink:to="srt_RangeAxis_lbl" />
    <link:label xml:lang="en-US" xlink:label="srt_RangeAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Range [Axis]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_RangeMember" xlink:type="locator" xlink:label="srt_RangeMember" />
    <link:label xml:lang="en-US" xlink:label="srt_RangeMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Statistical Measurement</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="srt_RangeMember" xlink:to="srt_RangeMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="srt_RangeMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Range [Member]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_MinimumMember" xlink:type="locator" xlink:label="srt_MinimumMember" />
    <link:label xml:lang="en-US" xlink:label="srt_MinimumMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Minimum</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="srt_MinimumMember" xlink:to="srt_MinimumMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="srt_MinimumMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Minimum [Member]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_MaximumMember" xlink:type="locator" xlink:label="srt_MaximumMember" />
    <link:label xml:lang="en-US" xlink:label="srt_MaximumMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Maximum</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="srt_MaximumMember" xlink:to="srt_MaximumMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="srt_MaximumMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Maximum [Member]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ConcentrationRiskByBenchmarkAxis" xlink:type="locator" xlink:label="us-gaap_ConcentrationRiskByBenchmarkAxis" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ConcentrationRiskByBenchmarkAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Concentration Risk Benchmark</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ConcentrationRiskByBenchmarkAxis" xlink:to="us-gaap_ConcentrationRiskByBenchmarkAxis_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ConcentrationRiskByBenchmarkAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Concentration Risk By Benchmark [Axis]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ConcentrationRiskBenchmarkDomain" xlink:type="locator" xlink:label="us-gaap_ConcentrationRiskBenchmarkDomain" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ConcentrationRiskBenchmarkDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Concentration Risk Benchmark</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ConcentrationRiskBenchmarkDomain" xlink:to="us-gaap_ConcentrationRiskBenchmarkDomain_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ConcentrationRiskBenchmarkDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Concentration Risk Benchmark [Domain]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_SalesRevenueNetMember" xlink:type="locator" xlink:label="us-gaap_SalesRevenueNetMember" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_SalesRevenueNetMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Revenue Benchmark</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SalesRevenueNetMember" xlink:to="us-gaap_SalesRevenueNetMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_SalesRevenueNetMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Sales Revenue Net [Member]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AccountsReceivableMember" xlink:type="locator" xlink:label="us-gaap_AccountsReceivableMember" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_AccountsReceivableMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Accounts Receivable</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AccountsReceivableMember" xlink:to="us-gaap_AccountsReceivableMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_AccountsReceivableMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Accounts Receivable [Member]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ConcentrationRiskByTypeAxis" xlink:type="locator" xlink:label="us-gaap_ConcentrationRiskByTypeAxis" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ConcentrationRiskByTypeAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Concentration Risk Type</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ConcentrationRiskByTypeAxis" xlink:to="us-gaap_ConcentrationRiskByTypeAxis_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ConcentrationRiskByTypeAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Concentration Risk By Type [Axis]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ConcentrationRiskTypeDomain" xlink:type="locator" xlink:label="us-gaap_ConcentrationRiskTypeDomain" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ConcentrationRiskTypeDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Concentration Risk Type</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ConcentrationRiskTypeDomain" xlink:to="us-gaap_ConcentrationRiskTypeDomain_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ConcentrationRiskTypeDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Concentration Risk Type [Domain]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CreditConcentrationRiskMember" xlink:type="locator" xlink:label="us-gaap_CreditConcentrationRiskMember" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_CreditConcentrationRiskMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Concentration of Credit Risk</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_CreditConcentrationRiskMember" xlink:to="us-gaap_CreditConcentrationRiskMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_CreditConcentrationRiskMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Credit Concentration Risk [Member]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_InitialApplicationPeriodCumulativeEffectTransitionAxis" xlink:type="locator" xlink:label="us-gaap_InitialApplicationPeriodCumulativeEffectTransitionAxis" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_InitialApplicationPeriodCumulativeEffectTransitionAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Initial Application Period Cumulative Effect Transition</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_InitialApplicationPeriodCumulativeEffectTransitionAxis" xlink:to="us-gaap_InitialApplicationPeriodCumulativeEffectTransitionAxis_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_InitialApplicationPeriodCumulativeEffectTransitionAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Initial Application Period Cumulative Effect Transition [Axis]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_InitialApplicationPeriodCumulativeEffectTransitionDomain" xlink:type="locator" xlink:label="us-gaap_InitialApplicationPeriodCumulativeEffectTransitionDomain" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_InitialApplicationPeriodCumulativeEffectTransitionDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Initial Application Period Cumulative Effect Transition</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_InitialApplicationPeriodCumulativeEffectTransitionDomain" xlink:to="us-gaap_InitialApplicationPeriodCumulativeEffectTransitionDomain_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_InitialApplicationPeriodCumulativeEffectTransitionDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Initial Application Period Cumulative Effect Transition [Domain]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DifferenceBetweenRevenueGuidanceInEffectBeforeAndAfterTopic606Member" xlink:type="locator" xlink:label="us-gaap_DifferenceBetweenRevenueGuidanceInEffectBeforeAndAfterTopic606Member" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DifferenceBetweenRevenueGuidanceInEffectBeforeAndAfterTopic606Member_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Difference between Revenue Guidance in Effect before and after Topic 606</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DifferenceBetweenRevenueGuidanceInEffectBeforeAndAfterTopic606Member" xlink:to="us-gaap_DifferenceBetweenRevenueGuidanceInEffectBeforeAndAfterTopic606Member_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DifferenceBetweenRevenueGuidanceInEffectBeforeAndAfterTopic606Member_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Difference Between Revenue Guidance In Effect Before And After Topic606 [Member]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BalanceSheetLocationAxis" xlink:type="locator" xlink:label="us-gaap_BalanceSheetLocationAxis" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_BalanceSheetLocationAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Balance Sheet Location</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_BalanceSheetLocationAxis" xlink:to="us-gaap_BalanceSheetLocationAxis_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_BalanceSheetLocationAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Balance Sheet Location [Axis]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BalanceSheetLocationDomain" xlink:type="locator" xlink:label="us-gaap_BalanceSheetLocationDomain" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_BalanceSheetLocationDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Balance Sheet Location</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_BalanceSheetLocationDomain" xlink:to="us-gaap_BalanceSheetLocationDomain_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_BalanceSheetLocationDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Balance Sheet Location [Domain]</link:label>
    <link:loc xlink:href="psn-20191231.xsd#psn_ContractWithCustomerAssetMember" xlink:type="locator" xlink:label="psn_ContractWithCustomerAssetMember" />
    <link:label xml:lang="en-US" xlink:label="psn_ContractWithCustomerAssetMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Contract with customer asset.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="psn_ContractWithCustomerAssetMember" xlink:to="psn_ContractWithCustomerAssetMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="psn_ContractWithCustomerAssetMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Increase to Contract Assets</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_ContractWithCustomerAssetMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Contract With Customer Asset [Member]</link:label>
    <link:loc xlink:href="psn-20191231.xsd#psn_DeferredTaxAssetsMember" xlink:type="locator" xlink:label="psn_DeferredTaxAssetsMember" />
    <link:label xml:lang="en-US" xlink:label="psn_DeferredTaxAssetsMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Deferred tax assets.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="psn_DeferredTaxAssetsMember" xlink:to="psn_DeferredTaxAssetsMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="psn_DeferredTaxAssetsMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Increase to Deferred Tax Assets</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_DeferredTaxAssetsMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Deferred Tax Assets [Member]</link:label>
    <link:loc xlink:href="psn-20191231.xsd#psn_ContractWithCustomerLiabilitiesMember" xlink:type="locator" xlink:label="psn_ContractWithCustomerLiabilitiesMember" />
    <link:label xml:lang="en-US" xlink:label="psn_ContractWithCustomerLiabilitiesMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Contract with customer liabilities.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="psn_ContractWithCustomerLiabilitiesMember" xlink:to="psn_ContractWithCustomerLiabilitiesMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="psn_ContractWithCustomerLiabilitiesMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Increase to Contract Liabilities</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_ContractWithCustomerLiabilitiesMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Contract With Customer Liabilities [Member]</link:label>
    <link:loc xlink:href="psn-20191231.xsd#psn_NonControllingInterestsMember" xlink:type="locator" xlink:label="psn_NonControllingInterestsMember" />
    <link:label xml:lang="en-US" xlink:label="psn_NonControllingInterestsMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Non Controlling interests.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="psn_NonControllingInterestsMember" xlink:to="psn_NonControllingInterestsMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="psn_NonControllingInterestsMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Increase to Non-controlling Interests</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_NonControllingInterestsMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Non Controlling Interests [Member]</link:label>
    <link:label xml:lang="en-US" xlink:label="us-gaap_AccountingStandardsUpdate201602Member_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Accounting Standards Update 2016-02</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ValuationAllowanceByDeferredTaxAssetAxis" xlink:type="locator" xlink:label="us-gaap_ValuationAllowanceByDeferredTaxAssetAxis" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ValuationAllowanceByDeferredTaxAssetAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Valuation Allowance by Deferred Tax Asset</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ValuationAllowanceByDeferredTaxAssetAxis" xlink:to="us-gaap_ValuationAllowanceByDeferredTaxAssetAxis_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ValuationAllowanceByDeferredTaxAssetAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Valuation Allowance By Deferred Tax Asset [Axis]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DeferredTaxAssetDomain" xlink:type="locator" xlink:label="us-gaap_DeferredTaxAssetDomain" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DeferredTaxAssetDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Deferred Tax Asset</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DeferredTaxAssetDomain" xlink:to="us-gaap_DeferredTaxAssetDomain_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DeferredTaxAssetDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Deferred Tax Asset [Domain]</link:label>
    <link:loc xlink:href="psn-20191231.xsd#psn_NetDeferredTaxAssetMember" xlink:type="locator" xlink:label="psn_NetDeferredTaxAssetMember" />
    <link:label xml:lang="en-US" xlink:label="psn_NetDeferredTaxAssetMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Net deferred tax asset.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="psn_NetDeferredTaxAssetMember" xlink:to="psn_NetDeferredTaxAssetMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="psn_NetDeferredTaxAssetMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Net Deferred Tax Asset</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_NetDeferredTaxAssetMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Net Deferred Tax Asset [Member]</link:label>
    <link:loc xlink:href="psn-20191231.xsd#psn_DeferredTaxAssetMember" xlink:type="locator" xlink:label="psn_DeferredTaxAssetMember" />
    <link:label xml:lang="en-US" xlink:label="psn_DeferredTaxAssetMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Deferred tax asset.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="psn_DeferredTaxAssetMember" xlink:to="psn_DeferredTaxAssetMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="psn_DeferredTaxAssetMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Deferred Tax Asset</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_DeferredTaxAssetMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Deferred Tax Asset [Member]</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_SignificantAccountingPoliciesLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Significant Accounting Policies [Line Items]</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_SignificantAccountingPoliciesLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Significant Accounting Policies [Line Items]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_EmployeeStockOwnershipPlanESOPSharesContributedToESOP" xlink:type="locator" xlink:label="us-gaap_EmployeeStockOwnershipPlanESOPSharesContributedToESOP" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_EmployeeStockOwnershipPlanESOPSharesContributedToESOP_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Contributions to ESOP</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_EmployeeStockOwnershipPlanESOPSharesContributedToESOP" xlink:to="us-gaap_EmployeeStockOwnershipPlanESOPSharesContributedToESOP_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_EmployeeStockOwnershipPlanESOPSharesContributedToESOP_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Employee Stock Ownership Plan E S O P Shares Contributed To E S O P</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_TreasuryStockCommonShares" xlink:type="locator" xlink:label="us-gaap_TreasuryStockCommonShares" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_TreasuryStockCommonShares_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Repurchase of shares of common stock from ESOP</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_TreasuryStockCommonShares" xlink:to="us-gaap_TreasuryStockCommonShares_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_TreasuryStockCommonShares_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Treasury Stock Common Shares</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_EmployeeStockOwnershipPlanESOPRepurchaseObligationAmount" xlink:type="locator" xlink:label="us-gaap_EmployeeStockOwnershipPlanESOPRepurchaseObligationAmount" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_EmployeeStockOwnershipPlanESOPRepurchaseObligationAmount_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Redemption value of ESOP participants interest</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_EmployeeStockOwnershipPlanESOPRepurchaseObligationAmount" xlink:to="us-gaap_EmployeeStockOwnershipPlanESOPRepurchaseObligationAmount_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_EmployeeStockOwnershipPlanESOPRepurchaseObligationAmount_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Employee Stock Ownership Plan E S O P Repurchase Obligation Amount</link:label>
    <link:loc xlink:href="psn-20191231.xsd#psn_RevenuePerformanceObligationPaymentTerms" xlink:type="locator" xlink:label="psn_RevenuePerformanceObligationPaymentTerms" />
    <link:label xml:lang="en-US" xlink:label="psn_RevenuePerformanceObligationPaymentTerms_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Revenue performance obligation payment terms.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="psn_RevenuePerformanceObligationPaymentTerms" xlink:to="psn_RevenuePerformanceObligationPaymentTerms_lbl" />
    <link:label xml:lang="en-US" xlink:label="psn_RevenuePerformanceObligationPaymentTerms_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Performance obligations payment terms from date of invoice</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_RevenuePerformanceObligationPaymentTerms_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Revenue Performance Obligation Payment Terms</link:label>
    <link:loc xlink:href="psn-20191231.xsd#psn_NumberOfCustomersRepresentingTenPercentOrMoreOfRevenues" xlink:type="locator" xlink:label="psn_NumberOfCustomersRepresentingTenPercentOrMoreOfRevenues" />
    <link:label xml:lang="en-US" xlink:label="psn_NumberOfCustomersRepresentingTenPercentOrMoreOfRevenues_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Number of customers representing ten percent or more of revenues.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="psn_NumberOfCustomersRepresentingTenPercentOrMoreOfRevenues" xlink:to="psn_NumberOfCustomersRepresentingTenPercentOrMoreOfRevenues_lbl" />
    <link:loc xlink:href="psn-20191231.xsd#psn_NumberOfCustomersRepresentingTenPercentOrMoreOfAccountsReceivable" xlink:type="locator" xlink:label="psn_NumberOfCustomersRepresentingTenPercentOrMoreOfAccountsReceivable" />
    <link:label xml:lang="en-US" xlink:label="psn_NumberOfCustomersRepresentingTenPercentOrMoreOfAccountsReceivable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Number of customers representing ten percent or more of accounts receivable.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="psn_NumberOfCustomersRepresentingTenPercentOrMoreOfAccountsReceivable" xlink:to="psn_NumberOfCustomersRepresentingTenPercentOrMoreOfAccountsReceivable_lbl" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ConcentrationRiskPercentage1" xlink:type="locator" xlink:label="us-gaap_ConcentrationRiskPercentage1" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ConcentrationRiskPercentage1_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Concentration risk percentage</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ConcentrationRiskPercentage1" xlink:to="us-gaap_ConcentrationRiskPercentage1_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ConcentrationRiskPercentage1_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Concentration Risk Percentage1</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_NumberOfCustomersRepresentingTenPercentOrMoreOfRevenues_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Number of customers representing more than 10% of revenue</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_NumberOfCustomersRepresentingTenPercentOrMoreOfRevenues_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Number Of Customers Representing Ten Percent Or More Of Revenues</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_NumberOfCustomersRepresentingTenPercentOrMoreOfAccountsReceivable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Number of customers representing more than 10% of accounts receivable</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_NumberOfCustomersRepresentingTenPercentOrMoreOfAccountsReceivable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Number Of Customers Representing Ten Percent Or More Of Accounts Receivable</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife" xlink:type="locator" xlink:label="us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel">Intangible assets useful lives of underlying assets</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife" xlink:to="us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Acquired Finite Lived Intangible Assets Weighted Average Useful Life</link:label>
    <link:label xml:lang="en-US" xlink:label="us-gaap_RetainedEarningsAccumulatedDeficit_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel">Increase in retained earnings</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption" xlink:type="locator" xlink:label="us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Cumulative effect adjustments</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption" xlink:to="us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Cumulative Effect Of New Accounting Principle In Period Of Adoption</link:label>
    <link:label xml:lang="en-US" xlink:label="us-gaap_NewAccountingPronouncementOrChangeInAccountingPrincipleEffectOfAdoptionQuantification_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel">Adoption of ASC 606</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable" xlink:type="locator" xlink:label="us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Schedule Of Business Acquisitions By Acquisition [Table]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable" xlink:to="us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Schedule Of Business Acquisitions By Acquisition [Table]</link:label>
    <link:loc xlink:href="psn-20191231.xsd#psn_WilliamsElectricCompanyIncorporationMember" xlink:type="locator" xlink:label="psn_WilliamsElectricCompanyIncorporationMember" />
    <link:label xml:lang="en-US" xlink:label="psn_WilliamsElectricCompanyIncorporationMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Williams electric company incorporation.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="psn_WilliamsElectricCompanyIncorporationMember" xlink:to="psn_WilliamsElectricCompanyIncorporationMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="psn_WilliamsElectricCompanyIncorporationMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Williams Electric Company, Inc.</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_WilliamsElectricCompanyIncorporationMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Williams Electric Company Incorporation [Member]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IncomeStatementLocationAxis" xlink:type="locator" xlink:label="us-gaap_IncomeStatementLocationAxis" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_IncomeStatementLocationAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Income Statement Location</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_IncomeStatementLocationAxis" xlink:to="us-gaap_IncomeStatementLocationAxis_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_IncomeStatementLocationAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Income Statement Location [Axis]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IncomeStatementLocationDomain" xlink:type="locator" xlink:label="us-gaap_IncomeStatementLocationDomain" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_IncomeStatementLocationDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Income Statement Location</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_IncomeStatementLocationDomain" xlink:to="us-gaap_IncomeStatementLocationDomain_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_IncomeStatementLocationDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Income Statement Location [Domain]</link:label>
    <link:loc xlink:href="psn-20191231.xsd#psn_IndirectGeneralAndAdministrativeExpenseMember" xlink:type="locator" xlink:label="psn_IndirectGeneralAndAdministrativeExpenseMember" />
    <link:label xml:lang="en-US" xlink:label="psn_IndirectGeneralAndAdministrativeExpenseMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Indirect, General and Administrative Expense.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="psn_IndirectGeneralAndAdministrativeExpenseMember" xlink:to="psn_IndirectGeneralAndAdministrativeExpenseMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="psn_IndirectGeneralAndAdministrativeExpenseMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Indirect, General and Administrative Expense</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_IndirectGeneralAndAdministrativeExpenseMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Indirect General And Administrative Expense [Member]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShortTermDebtTypeAxis" xlink:type="locator" xlink:label="us-gaap_ShortTermDebtTypeAxis" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShortTermDebtTypeAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Short-term Debt, Type</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShortTermDebtTypeAxis" xlink:to="us-gaap_ShortTermDebtTypeAxis_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShortTermDebtTypeAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Short Term Debt Type [Axis]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShortTermDebtTypeDomain" xlink:type="locator" xlink:label="us-gaap_ShortTermDebtTypeDomain" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShortTermDebtTypeDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Short-term Debt, Type</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShortTermDebtTypeDomain" xlink:to="us-gaap_ShortTermDebtTypeDomain_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShortTermDebtTypeDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Short Term Debt Type [Domain]</link:label>
    <link:loc xlink:href="psn-20191231.xsd#psn_TermLoanMember" xlink:type="locator" xlink:label="psn_TermLoanMember" />
    <link:label xml:lang="en-US" xlink:label="psn_TermLoanMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Term loan.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="psn_TermLoanMember" xlink:to="psn_TermLoanMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="psn_TermLoanMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Term Loan</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_TermLoanMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Term Loan [Member]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CreditFacilityAxis" xlink:type="locator" xlink:label="us-gaap_CreditFacilityAxis" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_CreditFacilityAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Credit Facility</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_CreditFacilityAxis" xlink:to="us-gaap_CreditFacilityAxis_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_CreditFacilityAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Credit Facility [Axis]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CreditFacilityDomain" xlink:type="locator" xlink:label="us-gaap_CreditFacilityDomain" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_CreditFacilityDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Credit Facility</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_CreditFacilityDomain" xlink:to="us-gaap_CreditFacilityDomain_lbl" />
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    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FixedPriceContractMember" xlink:type="locator" xlink:label="us-gaap_FixedPriceContractMember" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_FixedPriceContractMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Fixed-Price</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FixedPriceContractMember" xlink:to="us-gaap_FixedPriceContractMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_FixedPriceContractMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Fixed Price Contract [Member]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DisaggregationOfRevenueLineItems" xlink:type="locator" xlink:label="us-gaap_DisaggregationOfRevenueLineItems" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DisaggregationOfRevenueLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Disaggregation Of Revenue [Line Items]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DisaggregationOfRevenueLineItems" xlink:to="us-gaap_DisaggregationOfRevenueLineItems_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DisaggregationOfRevenueLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Disaggregation Of Revenue [Line Items]</link:label>
    <link:label xml:lang="en-US" xlink:label="us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel">Revenues</link:label>
    <link:loc xlink:href="psn-20191231.xsd#psn_ContractWithCustomerAssetLiabilityNet" xlink:type="locator" xlink:label="psn_ContractWithCustomerAssetLiabilityNet" />
    <link:label xml:lang="en-US" xlink:label="psn_ContractWithCustomerAssetLiabilityNet_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Contract with customer asset and liabilities net.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="psn_ContractWithCustomerAssetLiabilityNet" xlink:to="psn_ContractWithCustomerAssetLiabilityNet_lbl" />
    <link:loc xlink:href="psn-20191231.xsd#psn_ChangeInContractWithCustomerAssetsAndLiabilitiesNet" xlink:type="locator" xlink:label="psn_ChangeInContractWithCustomerAssetsAndLiabilitiesNet" />
    <link:label xml:lang="en-US" xlink:label="psn_ChangeInContractWithCustomerAssetsAndLiabilitiesNet_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Change in contract with customer assets and liabilities net.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="psn_ChangeInContractWithCustomerAssetsAndLiabilitiesNet" xlink:to="psn_ChangeInContractWithCustomerAssetsAndLiabilitiesNet_lbl" />
    <link:loc xlink:href="psn-20191231.xsd#psn_ChangeInContractWithCustomerAssets" xlink:type="locator" xlink:label="psn_ChangeInContractWithCustomerAssets" />
    <link:label xml:lang="en-US" xlink:label="psn_ChangeInContractWithCustomerAssets_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Change in contract with customer assets.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="psn_ChangeInContractWithCustomerAssets" xlink:to="psn_ChangeInContractWithCustomerAssets_lbl" />
    <link:loc xlink:href="psn-20191231.xsd#psn_ChangeInContractWithCustomerLiability" xlink:type="locator" xlink:label="psn_ChangeInContractWithCustomerLiability" />
    <link:label xml:lang="en-US" xlink:label="psn_ChangeInContractWithCustomerLiability_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Change in contract with customer liability.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="psn_ChangeInContractWithCustomerLiability" xlink:to="psn_ChangeInContractWithCustomerLiability_lbl" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ContractWithCustomerAssetNet" xlink:type="locator" xlink:label="us-gaap_ContractWithCustomerAssetNet" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ContractWithCustomerAssetNet_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Contract assets</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ContractWithCustomerAssetNet" xlink:to="us-gaap_ContractWithCustomerAssetNet_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ContractWithCustomerAssetNet_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Contract With Customer Asset Net</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ContractWithCustomerLiability" xlink:type="locator" xlink:label="us-gaap_ContractWithCustomerLiability" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ContractWithCustomerLiability_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Contract liabilities</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ContractWithCustomerLiability" xlink:to="us-gaap_ContractWithCustomerLiability_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ContractWithCustomerLiability_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Contract With Customer Liability</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_ContractWithCustomerAssetLiabilityNet_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Net contract assets (liabilities)</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_ContractWithCustomerAssetLiabilityNet_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Contract With Customer Asset Liability Net</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_ChangeInContractWithCustomerAssets_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Change in contract assets</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_ChangeInContractWithCustomerAssets_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Change In Contract With Customer Assets</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_ChangeInContractWithCustomerLiability_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Change in contract liabilities</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_ChangeInContractWithCustomerLiability_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Change In Contract With Customer Liability</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_ChangeInContractWithCustomerAssetsAndLiabilitiesNet_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Change in contract assets and liabilities</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_ChangeInContractWithCustomerAssetsAndLiabilitiesNet_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Change In Contract With Customer Assets And Liabilities Net</link:label>
    <link:loc xlink:href="psn-20191231.xsd#psn_ContractWithCustomerAssetCumulativeCatchupAdjustmentToRevenueChangeInMeasureOfProgressPercent" xlink:type="locator" xlink:label="psn_ContractWithCustomerAssetCumulativeCatchupAdjustmentToRevenueChangeInMeasureOfProgressPercent" />
    <link:label xml:lang="en-US" xlink:label="psn_ContractWithCustomerAssetCumulativeCatchupAdjustmentToRevenueChangeInMeasureOfProgressPercent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Contract with customer asset cumulative catchup adjustment to revenue change in measure of progress percent.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="psn_ContractWithCustomerAssetCumulativeCatchupAdjustmentToRevenueChangeInMeasureOfProgressPercent" xlink:to="psn_ContractWithCustomerAssetCumulativeCatchupAdjustmentToRevenueChangeInMeasureOfProgressPercent_lbl" />
    <link:loc xlink:href="psn-20191231.xsd#psn_ContractWithCustomerLiabilityCumulativeCatchupAdjustmentToRevenueChangeInMeasureOfProgressPercent" xlink:type="locator" xlink:label="psn_ContractWithCustomerLiabilityCumulativeCatchupAdjustmentToRevenueChangeInMeasureOfProgressPercent" />
    <link:label xml:lang="en-US" xlink:label="psn_ContractWithCustomerLiabilityCumulativeCatchupAdjustmentToRevenueChangeInMeasureOfProgressPercent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Contract with customer liability cumulative catchup adjustment to revenue change in measure of progress percent.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="psn_ContractWithCustomerLiabilityCumulativeCatchupAdjustmentToRevenueChangeInMeasureOfProgressPercent" xlink:to="psn_ContractWithCustomerLiabilityCumulativeCatchupAdjustmentToRevenueChangeInMeasureOfProgressPercent_lbl" />
    <link:loc xlink:href="psn-20191231.xsd#psn_ContractWithCustomerAssetLiabilityCumulativeCatchupAdjustmentToRevenueChangeInMeasureOfProgressPercent" xlink:type="locator" xlink:label="psn_ContractWithCustomerAssetLiabilityCumulativeCatchupAdjustmentToRevenueChangeInMeasureOfProgressPercent" />
    <link:label xml:lang="en-US" xlink:label="psn_ContractWithCustomerAssetLiabilityCumulativeCatchupAdjustmentToRevenueChangeInMeasureOfProgressPercent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Contract with customer asset cumulative catchup adjustment to revenue change in measure of progress percent.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="psn_ContractWithCustomerAssetLiabilityCumulativeCatchupAdjustmentToRevenueChangeInMeasureOfProgressPercent" xlink:to="psn_ContractWithCustomerAssetLiabilityCumulativeCatchupAdjustmentToRevenueChangeInMeasureOfProgressPercent_lbl" />
    <link:label xml:lang="en-US" xlink:label="psn_ContractWithCustomerAssetCumulativeCatchupAdjustmentToRevenueChangeInMeasureOfProgressPercent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Percentage change in contract assets</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_ContractWithCustomerAssetCumulativeCatchupAdjustmentToRevenueChangeInMeasureOfProgressPercent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Contract With Customer Asset Cumulative Catchup Adjustment To Revenue Change In Measure Of Progress Percent</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_ContractWithCustomerLiabilityCumulativeCatchupAdjustmentToRevenueChangeInMeasureOfProgressPercent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Percentage change in contract liabilities</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_ContractWithCustomerLiabilityCumulativeCatchupAdjustmentToRevenueChangeInMeasureOfProgressPercent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Contract With Customer Liability Cumulative Catchup Adjustment To Revenue Change In Measure Of Progress Percent</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_ContractWithCustomerAssetLiabilityCumulativeCatchupAdjustmentToRevenueChangeInMeasureOfProgressPercent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Percentage change in contract assets and liabilities</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_ContractWithCustomerAssetLiabilityCumulativeCatchupAdjustmentToRevenueChangeInMeasureOfProgressPercent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Contract With Customer Asset Liability Cumulative Catchup Adjustment To Revenue Change In Measure Of Progress Percent</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ContractReceivableRetainage" xlink:type="locator" xlink:label="us-gaap_ContractReceivableRetainage" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ContractReceivableRetainage_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Contract retentions</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ContractReceivableRetainage" xlink:to="us-gaap_ContractReceivableRetainage_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ContractReceivableRetainage_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Contract Receivable Retainage</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ContractReceivableRetainageDueAfterOneYear" xlink:type="locator" xlink:label="us-gaap_ContractReceivableRetainageDueAfterOneYear" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ContractReceivableRetainageDueAfterOneYear_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Contract retentions, not expected to be paid in next 12 months</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ContractReceivableRetainageDueAfterOneYear" xlink:to="us-gaap_ContractReceivableRetainageDueAfterOneYear_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ContractReceivableRetainageDueAfterOneYear_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Contract Receivable Retainage Due After One Year</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ContractsReceivableClaimsAndUncertainAmounts" xlink:type="locator" xlink:label="us-gaap_ContractsReceivableClaimsAndUncertainAmounts" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ContractsReceivableClaimsAndUncertainAmounts_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Contract assets, unapproved change orders, claims, and requests</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ContractsReceivableClaimsAndUncertainAmounts" xlink:to="us-gaap_ContractsReceivableClaimsAndUncertainAmounts_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ContractsReceivableClaimsAndUncertainAmounts_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Contracts Receivable Claims And Uncertain Amounts</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ContractWithCustomerLiabilityRevenueRecognized" xlink:type="locator" xlink:label="us-gaap_ContractWithCustomerLiabilityRevenueRecognized" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ContractWithCustomerLiabilityRevenueRecognized_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Revenue recognized included contract liability</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ContractWithCustomerLiabilityRevenueRecognized" xlink:to="us-gaap_ContractWithCustomerLiabilityRevenueRecognized_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ContractWithCustomerLiabilityRevenueRecognized_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Contract With Customer Liability Revenue Recognized</link:label>
    <link:loc xlink:href="psn-20191231.xsd#psn_ReversalOfProvisionForContractLosses" xlink:type="locator" xlink:label="psn_ReversalOfProvisionForContractLosses" />
    <link:label xml:lang="en-US" xlink:label="psn_ReversalOfProvisionForContractLosses_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Reversal of provision for contract losses.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="psn_ReversalOfProvisionForContractLosses" xlink:to="psn_ReversalOfProvisionForContractLosses_lbl" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ContractWithCustomerAssetIncreaseDecreaseForContractAcquiredInBusinessCombination" xlink:type="locator" xlink:label="us-gaap_ContractWithCustomerAssetIncreaseDecreaseForContractAcquiredInBusinessCombination" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ContractWithCustomerAssetIncreaseDecreaseForContractAcquiredInBusinessCombination_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Acquired contract assets</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ContractWithCustomerAssetIncreaseDecreaseForContractAcquiredInBusinessCombination" xlink:to="us-gaap_ContractWithCustomerAssetIncreaseDecreaseForContractAcquiredInBusinessCombination_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ContractWithCustomerAssetIncreaseDecreaseForContractAcquiredInBusinessCombination_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Contract With Customer Asset Increase Decrease For Contract Acquired In Business Combination</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ContractWithCustomerLiabilityIncreaseDecreaseForContractAcquiredInBusinessCombination" xlink:type="locator" xlink:label="us-gaap_ContractWithCustomerLiabilityIncreaseDecreaseForContractAcquiredInBusinessCombination" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ContractWithCustomerLiabilityIncreaseDecreaseForContractAcquiredInBusinessCombination_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Acquired contract liabilities</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ContractWithCustomerLiabilityIncreaseDecreaseForContractAcquiredInBusinessCombination" xlink:to="us-gaap_ContractWithCustomerLiabilityIncreaseDecreaseForContractAcquiredInBusinessCombination_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ContractWithCustomerLiabilityIncreaseDecreaseForContractAcquiredInBusinessCombination_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Contract With Customer Liability Increase Decrease For Contract Acquired In Business Combination</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ContractWithCustomerLiabilityCumulativeCatchUpAdjustmentToRevenueChangeInEstimateOfTransactionPrice" xlink:type="locator" xlink:label="us-gaap_ContractWithCustomerLiabilityCumulativeCatchUpAdjustmentToRevenueChangeInEstimateOfTransactionPrice" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ContractWithCustomerLiabilityCumulativeCatchUpAdjustmentToRevenueChangeInEstimateOfTransactionPrice_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Change in the estimate of variable consideration</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ContractWithCustomerLiabilityCumulativeCatchUpAdjustmentToRevenueChangeInEstimateOfTransactionPrice" xlink:to="us-gaap_ContractWithCustomerLiabilityCumulativeCatchUpAdjustmentToRevenueChangeInEstimateOfTransactionPrice_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ContractWithCustomerLiabilityCumulativeCatchUpAdjustmentToRevenueChangeInEstimateOfTransactionPrice_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Contract With Customer Liability Cumulative Catch Up Adjustment To Revenue Change In Estimate Of Transaction Price</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_ReversalOfProvisionForContractLosses_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Reversal of provision for contract losses</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_ReversalOfProvisionForContractLosses_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Reversal Of Provision For Contract Losses</link:label>
    <link:loc xlink:href="psn-20191231.xsd#psn_IncreaseInRevenueDueToReversalOfProvisionForContractLosses" xlink:type="locator" xlink:label="psn_IncreaseInRevenueDueToReversalOfProvisionForContractLosses" />
    <link:label xml:lang="en-US" xlink:label="psn_IncreaseInRevenueDueToReversalOfProvisionForContractLosses_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Increase in revenue due to reversal of provision for contract losses.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="psn_IncreaseInRevenueDueToReversalOfProvisionForContractLosses" xlink:to="psn_IncreaseInRevenueDueToReversalOfProvisionForContractLosses_lbl" />
    <link:label xml:lang="en-US" xlink:label="psn_ReversalOfProvisionForContractLosses_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel">Reversal for provision for contract losses</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_IncreaseInRevenueDueToReversalOfProvisionForContractLosses_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Increase in revenue recorded in other income</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_IncreaseInRevenueDueToReversalOfProvisionForContractLosses_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Increase In Revenue Due To Reversal Of Provision For Contract Losses</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CapitalizedContractCostImpairmentLoss" xlink:type="locator" xlink:label="us-gaap_CapitalizedContractCostImpairmentLoss" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_CapitalizedContractCostImpairmentLoss_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Impairment of contract assets</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_CapitalizedContractCostImpairmentLoss" xlink:to="us-gaap_CapitalizedContractCostImpairmentLoss_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_CapitalizedContractCostImpairmentLoss_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Capitalized Contract Cost Impairment Loss</link:label>
    <link:loc xlink:href="psn-20191231.xsd#psn_ContractWithCustomerAdjustmentToRevenueImpactOfChangesInEstimatedClaimsOrIncentivesOverThreshold" xlink:type="locator" xlink:label="psn_ContractWithCustomerAdjustmentToRevenueImpactOfChangesInEstimatedClaimsOrIncentivesOverThreshold" />
    <link:label xml:lang="en-US" xlink:label="psn_ContractWithCustomerAdjustmentToRevenueImpactOfChangesInEstimatedClaimsOrIncentivesOverThreshold_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Contract with customer adjustment to revenue impact of changes in estimated claims or incentives over threshold.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="psn_ContractWithCustomerAdjustmentToRevenueImpactOfChangesInEstimatedClaimsOrIncentivesOverThreshold" xlink:to="psn_ContractWithCustomerAdjustmentToRevenueImpactOfChangesInEstimatedClaimsOrIncentivesOverThreshold_lbl" />
    <link:label xml:lang="en-US" xlink:label="psn_ContractWithCustomerAdjustmentToRevenueImpactOfChangesInEstimatedClaimsOrIncentivesOverThreshold_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Impact of changes in estimated claims or incentives on revenue</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_ContractWithCustomerAdjustmentToRevenueImpactOfChangesInEstimatedClaimsOrIncentivesOverThreshold_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Contract With Customer Adjustment To Revenue Impact Of Changes In Estimated Claims Or Incentives Over Threshold</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ContractWithCustomerLiabilityCumulativeCatchUpAdjustmentToRevenueChangeInMeasureOfProgress" xlink:type="locator" xlink:label="us-gaap_ContractWithCustomerLiabilityCumulativeCatchUpAdjustmentToRevenueChangeInMeasureOfProgress" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ContractWithCustomerLiabilityCumulativeCatchUpAdjustmentToRevenueChangeInMeasureOfProgress_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Increase in revenue due to Impact of changes in estimated claims or incentives</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ContractWithCustomerLiabilityCumulativeCatchUpAdjustmentToRevenueChangeInMeasureOfProgress" xlink:to="us-gaap_ContractWithCustomerLiabilityCumulativeCatchUpAdjustmentToRevenueChangeInMeasureOfProgress_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ContractWithCustomerLiabilityCumulativeCatchUpAdjustmentToRevenueChangeInMeasureOfProgress_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Contract With Customer Liability Cumulative Catch Up Adjustment To Revenue Change In Measure Of Progress</link:label>
    <link:loc xlink:href="psn-20191231.xsd#psn_BilledReceivablesCurrent" xlink:type="locator" xlink:label="psn_BilledReceivablesCurrent" />
    <link:label xml:lang="en-US" xlink:label="psn_BilledReceivablesCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Billed receivables current.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="psn_BilledReceivablesCurrent" xlink:to="psn_BilledReceivablesCurrent_lbl" />
    <link:label xml:lang="en-US" xlink:label="psn_BilledReceivablesCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Billed</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_BilledReceivablesCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Billed Receivables Current</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_UnbilledReceivablesCurrent" xlink:type="locator" xlink:label="us-gaap_UnbilledReceivablesCurrent" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_UnbilledReceivablesCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Unbilled</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_UnbilledReceivablesCurrent" xlink:to="us-gaap_UnbilledReceivablesCurrent_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_UnbilledReceivablesCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Unbilled Receivables Current</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AccountsReceivableGrossCurrent" xlink:type="locator" xlink:label="us-gaap_AccountsReceivableGrossCurrent" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_AccountsReceivableGrossCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Total accounts receivable, gross</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AccountsReceivableGrossCurrent" xlink:to="us-gaap_AccountsReceivableGrossCurrent_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_AccountsReceivableGrossCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Accounts Receivable Gross Current</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AllowanceForDoubtfulAccountsReceivableCurrent" xlink:type="locator" xlink:label="us-gaap_AllowanceForDoubtfulAccountsReceivableCurrent" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_AllowanceForDoubtfulAccountsReceivableCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Allowance for doubtful accounts</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AllowanceForDoubtfulAccountsReceivableCurrent" xlink:to="us-gaap_AllowanceForDoubtfulAccountsReceivableCurrent_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_AllowanceForDoubtfulAccountsReceivableCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Allowance For Doubtful Accounts Receivable Current</link:label>
    <link:label xml:lang="en-US" xlink:label="us-gaap_AccountsReceivableNetCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Total accounts receivable, net</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_RevenueRemainingPerformanceObligation" xlink:type="locator" xlink:label="us-gaap_RevenueRemainingPerformanceObligation" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_RevenueRemainingPerformanceObligation_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Remaining unsatisfied performance obligations</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_RevenueRemainingPerformanceObligation" xlink:to="us-gaap_RevenueRemainingPerformanceObligation_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_RevenueRemainingPerformanceObligation_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Revenue Remaining Performance Obligation</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable" xlink:type="locator" xlink:label="us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Table]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable" xlink:to="us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Table]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementBusinessSegmentsAxis" xlink:type="locator" xlink:label="us-gaap_StatementBusinessSegmentsAxis" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_StatementBusinessSegmentsAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Segments</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_StatementBusinessSegmentsAxis" xlink:to="us-gaap_StatementBusinessSegmentsAxis_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_StatementBusinessSegmentsAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Statement Business Segments [Axis]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_SegmentDomain" xlink:type="locator" xlink:label="us-gaap_SegmentDomain" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_SegmentDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Segments</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SegmentDomain" xlink:to="us-gaap_SegmentDomain_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_SegmentDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Segment [Domain]</link:label>
    <link:loc xlink:href="psn-20191231.xsd#psn_FederalSolutionSegmentMember" xlink:type="locator" xlink:label="psn_FederalSolutionSegmentMember" />
    <link:label xml:lang="en-US" xlink:label="psn_FederalSolutionSegmentMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Federal Solution Segment.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="psn_FederalSolutionSegmentMember" xlink:to="psn_FederalSolutionSegmentMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="psn_FederalSolutionSegmentMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Federal Solution Segment</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_FederalSolutionSegmentMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Federal Solution Segment [Member]</link:label>
    <link:loc xlink:href="psn-20191231.xsd#psn_CriticalInfrastructureSegmentMember" xlink:type="locator" xlink:label="psn_CriticalInfrastructureSegmentMember" />
    <link:label xml:lang="en-US" xlink:label="psn_CriticalInfrastructureSegmentMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Critical Infrastructure Segment.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="psn_CriticalInfrastructureSegmentMember" xlink:to="psn_CriticalInfrastructureSegmentMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="psn_CriticalInfrastructureSegmentMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Critical Infrastructure</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_CriticalInfrastructureSegmentMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Critical Infrastructure Segment [Member]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionStartDateAxis" xlink:type="locator" xlink:label="us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionStartDateAxis" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionStartDateAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionStartDateAxis" xlink:to="us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionStartDateAxis_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionStartDateAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Revenue Remaining Performance Obligation Expected Timing Of Satisfaction Start Date [Axis]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems" xlink:type="locator" xlink:label="us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems" xlink:to="us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1" xlink:type="locator" xlink:label="us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Revenue, remaining performance obligation, expected timing of satisfaction, period</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1" xlink:to="us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Revenue Remaining Performance Obligation Expected Timing Of Satisfaction Period1</link:label>
    <link:loc xlink:href="psn-20191231.xsd#psn_LesseeLeaseTermOfContract" xlink:type="locator" xlink:label="psn_LesseeLeaseTermOfContract" />
    <link:label xml:lang="en-US" xlink:label="psn_LesseeLeaseTermOfContract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Lessee lease term of contract.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="psn_LesseeLeaseTermOfContract" xlink:to="psn_LesseeLeaseTermOfContract_lbl" />
    <link:loc xlink:href="psn-20191231.xsd#psn_LesseeLeaseOptionToExtend" xlink:type="locator" xlink:label="psn_LesseeLeaseOptionToExtend" />
    <link:label xml:lang="en-US" xlink:label="psn_LesseeLeaseOptionToExtend_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Lessee lease option to extend.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="psn_LesseeLeaseOptionToExtend" xlink:to="psn_LesseeLeaseOptionToExtend_lbl" />
    <link:loc xlink:href="psn-20191231.xsd#psn_LesseeLeaseExistenceOfOptionToExtend" xlink:type="locator" xlink:label="psn_LesseeLeaseExistenceOfOptionToExtend" />
    <link:label xml:lang="en-US" xlink:label="psn_LesseeLeaseExistenceOfOptionToExtend_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Lessee lease existence of option to extend.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="psn_LesseeLeaseExistenceOfOptionToExtend" xlink:to="psn_LesseeLeaseExistenceOfOptionToExtend_lbl" />
    <link:loc xlink:href="psn-20191231.xsd#psn_LesseeLeaseOptionToTerminate" xlink:type="locator" xlink:label="psn_LesseeLeaseOptionToTerminate" />
    <link:label xml:lang="en-US" xlink:label="psn_LesseeLeaseOptionToTerminate_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Lessee lease option to terminate.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="psn_LesseeLeaseOptionToTerminate" xlink:to="psn_LesseeLeaseOptionToTerminate_lbl" />
    <link:loc xlink:href="psn-20191231.xsd#psn_LesseeLeaseExistenceOfOptionToTerminate" xlink:type="locator" xlink:label="psn_LesseeLeaseExistenceOfOptionToTerminate" />
    <link:label xml:lang="en-US" xlink:label="psn_LesseeLeaseExistenceOfOptionToTerminate_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Lessee lease existence of option to terminate.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="psn_LesseeLeaseExistenceOfOptionToTerminate" xlink:to="psn_LesseeLeaseExistenceOfOptionToTerminate_lbl" />
    <link:loc xlink:href="psn-20191231.xsd#psn_FinanceLeaseRightOfUseAssetsAccumulatedDepreciation" xlink:type="locator" xlink:label="psn_FinanceLeaseRightOfUseAssetsAccumulatedDepreciation" />
    <link:label xml:lang="en-US" xlink:label="psn_FinanceLeaseRightOfUseAssetsAccumulatedDepreciation_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Finance lease right of use assets accumulated depreciation.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="psn_FinanceLeaseRightOfUseAssetsAccumulatedDepreciation" xlink:to="psn_FinanceLeaseRightOfUseAssetsAccumulatedDepreciation_lbl" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LesseeLeaseDescriptionTable" xlink:type="locator" xlink:label="us-gaap_LesseeLeaseDescriptionTable" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LesseeLeaseDescriptionTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Lessee Lease Description [Table]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LesseeLeaseDescriptionTable" xlink:to="us-gaap_LesseeLeaseDescriptionTable_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LesseeLeaseDescriptionTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Lessee Lease Description [Table]</link:label>
    <link:loc xlink:href="psn-20191231.xsd#psn_IndirectGeneralAndAdministrativeExpensesMember" xlink:type="locator" xlink:label="psn_IndirectGeneralAndAdministrativeExpensesMember" />
    <link:label xml:lang="en-US" xlink:label="psn_IndirectGeneralAndAdministrativeExpensesMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Indirect, general and administrative expenses.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="psn_IndirectGeneralAndAdministrativeExpensesMember" xlink:to="psn_IndirectGeneralAndAdministrativeExpensesMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="psn_IndirectGeneralAndAdministrativeExpensesMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Indirect General And Administrative Expenses</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_IndirectGeneralAndAdministrativeExpensesMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Indirect General And Administrative Expenses [Member]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LesseeLeaseDescriptionLineItems" xlink:type="locator" xlink:label="us-gaap_LesseeLeaseDescriptionLineItems" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LesseeLeaseDescriptionLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Lessee Lease Description [Line Items]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LesseeLeaseDescriptionLineItems" xlink:to="us-gaap_LesseeLeaseDescriptionLineItems_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LesseeLeaseDescriptionLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Lessee Lease Description [Line Items]</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_LesseeLeaseTermOfContract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Lease term of contract</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_LesseeLeaseTermOfContract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Lessee Lease Term Of Contract</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_LesseeLeaseOptionToExtend_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Lease option to extend</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_LesseeLeaseOptionToExtend_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Lessee Lease Option To Extend</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_LesseeLeaseExistenceOfOptionToExtend_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Lease existence of option to extend</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_LesseeLeaseExistenceOfOptionToExtend_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Lessee Lease Existence Of Option To Extend</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_LesseeLeaseOptionToTerminate_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Lease option to terminate</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_LesseeLeaseOptionToTerminate_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Lessee Lease Option To Terminate</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_LesseeLeaseExistenceOfOptionToTerminate_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Lease existence of option to terminate</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_LesseeLeaseExistenceOfOptionToTerminate_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Lessee Lease Existence Of Option To Terminate</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FinanceLeaseRightOfUseAsset" xlink:type="locator" xlink:label="us-gaap_FinanceLeaseRightOfUseAsset" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_FinanceLeaseRightOfUseAsset_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Finance lease right-of-use asset</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FinanceLeaseRightOfUseAsset" xlink:to="us-gaap_FinanceLeaseRightOfUseAsset_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_FinanceLeaseRightOfUseAsset_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Finance Lease Right Of Use Asset</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_FinanceLeaseRightOfUseAssetsAccumulatedDepreciation_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Finance lease right of use assets accumulated depreciation</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_FinanceLeaseRightOfUseAssetsAccumulatedDepreciation_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Finance Lease Right Of Use Assets Accumulated Depreciation</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OperatingLeaseCost" xlink:type="locator" xlink:label="us-gaap_OperatingLeaseCost" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_OperatingLeaseCost_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Operating lease cost</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OperatingLeaseCost" xlink:to="us-gaap_OperatingLeaseCost_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_OperatingLeaseCost_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Operating Lease Cost</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShortTermLeaseCost" xlink:type="locator" xlink:label="us-gaap_ShortTermLeaseCost" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShortTermLeaseCost_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Short-term lease cost</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShortTermLeaseCost" xlink:to="us-gaap_ShortTermLeaseCost_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShortTermLeaseCost_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Short Term Lease Cost</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FinanceLeaseRightOfUseAssetAmortization" xlink:type="locator" xlink:label="us-gaap_FinanceLeaseRightOfUseAssetAmortization" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_FinanceLeaseRightOfUseAssetAmortization_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Amortization of right-of-use assets</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FinanceLeaseRightOfUseAssetAmortization" xlink:to="us-gaap_FinanceLeaseRightOfUseAssetAmortization_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_FinanceLeaseRightOfUseAssetAmortization_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Finance Lease Right Of Use Asset Amortization</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FinanceLeaseInterestPaymentOnLiability" xlink:type="locator" xlink:label="us-gaap_FinanceLeaseInterestPaymentOnLiability" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_FinanceLeaseInterestPaymentOnLiability_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Interest on lease liabilities</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FinanceLeaseInterestPaymentOnLiability" xlink:to="us-gaap_FinanceLeaseInterestPaymentOnLiability_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_FinanceLeaseInterestPaymentOnLiability_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Finance Lease Interest Payment On Liability</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_SubleaseIncome" xlink:type="locator" xlink:label="us-gaap_SubleaseIncome" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_SubleaseIncome_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Sublease income</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SubleaseIncome" xlink:to="us-gaap_SubleaseIncome_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_SubleaseIncome_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Sublease Income</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LeaseCost" xlink:type="locator" xlink:label="us-gaap_LeaseCost" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LeaseCost_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Total lease cost</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LeaseCost" xlink:to="us-gaap_LeaseCost_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LeaseCost_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Lease Cost</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OperatingLeasePayments" xlink:type="locator" xlink:label="us-gaap_OperatingLeasePayments" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_OperatingLeasePayments_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Operating cash flows for operating leases</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OperatingLeasePayments" xlink:to="us-gaap_OperatingLeasePayments_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_OperatingLeasePayments_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Operating Lease Payments</link:label>
    <link:label xml:lang="en-US" xlink:label="us-gaap_FinanceLeaseInterestPaymentOnLiability_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel">Operating cash flows for financing activities</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FinanceLeasePrincipalPayments" xlink:type="locator" xlink:label="us-gaap_FinanceLeasePrincipalPayments" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_FinanceLeasePrincipalPayments_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Financing cash flows from finance leases</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FinanceLeasePrincipalPayments" xlink:to="us-gaap_FinanceLeasePrincipalPayments_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_FinanceLeasePrincipalPayments_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Finance Lease Principal Payments</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability" xlink:type="locator" xlink:label="us-gaap_RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Right-of-use assets obtained in exchange for new operating lease liabilities</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability" xlink:to="us-gaap_RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Right Of Use Asset Obtained In Exchange For Operating Lease Liability</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_RightOfUseAssetObtainedInExchangeForFinanceLeaseLiability" xlink:type="locator" xlink:label="us-gaap_RightOfUseAssetObtainedInExchangeForFinanceLeaseLiability" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_RightOfUseAssetObtainedInExchangeForFinanceLeaseLiability_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Right-of-use assets obtained in exchange for new finance lease liabilities</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_RightOfUseAssetObtainedInExchangeForFinanceLeaseLiability" xlink:to="us-gaap_RightOfUseAssetObtainedInExchangeForFinanceLeaseLiability_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_RightOfUseAssetObtainedInExchangeForFinanceLeaseLiability_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Right Of Use Asset Obtained In Exchange For Finance Lease Liability</link:label>
    <link:loc xlink:href="psn-20191231.xsd#psn_OperatingLeasesAbstract" xlink:type="locator" xlink:label="psn_OperatingLeasesAbstract" />
    <link:label xml:lang="en-US" xlink:label="psn_OperatingLeasesAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Operating lease.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="psn_OperatingLeasesAbstract" xlink:to="psn_OperatingLeasesAbstract_lbl" />
    <link:loc xlink:href="psn-20191231.xsd#psn_LeaseLiabilitiesAbstract" xlink:type="locator" xlink:label="psn_LeaseLiabilitiesAbstract" />
    <link:label xml:lang="en-US" xlink:label="psn_LeaseLiabilitiesAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Lease liabilities.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="psn_LeaseLiabilitiesAbstract" xlink:to="psn_LeaseLiabilitiesAbstract_lbl" />
    <link:loc xlink:href="psn-20191231.xsd#psn_FinanceLeasesAbstract" xlink:type="locator" xlink:label="psn_FinanceLeasesAbstract" />
    <link:label xml:lang="en-US" xlink:label="psn_FinanceLeasesAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Finance leases.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="psn_FinanceLeasesAbstract" xlink:to="psn_FinanceLeasesAbstract_lbl" />
    <link:loc xlink:href="psn-20191231.xsd#psn_FinanceLeasesOtherAssetsNoncurrent" xlink:type="locator" xlink:label="psn_FinanceLeasesOtherAssetsNoncurrent" />
    <link:label xml:lang="en-US" xlink:label="psn_FinanceLeasesOtherAssetsNoncurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Finance leases other assets noncurrent.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="psn_FinanceLeasesOtherAssetsNoncurrent" xlink:to="psn_FinanceLeasesOtherAssetsNoncurrent_lbl" />
    <link:loc xlink:href="psn-20191231.xsd#psn_WeightedAverageRemainingLeaseTermAbstract" xlink:type="locator" xlink:label="psn_WeightedAverageRemainingLeaseTermAbstract" />
    <link:label xml:lang="en-US" xlink:label="psn_WeightedAverageRemainingLeaseTermAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Weighted average remaining lease term.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="psn_WeightedAverageRemainingLeaseTermAbstract" xlink:to="psn_WeightedAverageRemainingLeaseTermAbstract_lbl" />
    <link:loc xlink:href="psn-20191231.xsd#psn_WeightedAverageDiscountRateAbstract" xlink:type="locator" xlink:label="psn_WeightedAverageDiscountRateAbstract" />
    <link:label xml:lang="en-US" xlink:label="psn_WeightedAverageDiscountRateAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Weighted average discount rate.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="psn_WeightedAverageDiscountRateAbstract" xlink:to="psn_WeightedAverageDiscountRateAbstract_lbl" />
    <link:label xml:lang="en-US" xlink:label="psn_OperatingLeasesAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Operating Leases:</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_OperatingLeasesAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Operating Leases [Abstract]</link:label>
    <link:label xml:lang="en-US" xlink:label="us-gaap_OperatingLeaseRightOfUseAsset_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel">Right-of-use assets</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_LeaseLiabilitiesAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Lease liabilities:</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_LeaseLiabilitiesAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Lease Liabilities [Abstract]</link:label>
    <link:label xml:lang="en-US" xlink:label="us-gaap_OperatingLeaseLiabilityCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel">Current</link:label>
    <link:label xml:lang="en-US" xlink:label="us-gaap_OperatingLeaseLiabilityNoncurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel">Long-term</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OperatingLeaseLiability" xlink:type="locator" xlink:label="us-gaap_OperatingLeaseLiability" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_OperatingLeaseLiability_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Total operating lease liabilities</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OperatingLeaseLiability" xlink:to="us-gaap_OperatingLeaseLiability_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_OperatingLeaseLiability_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Operating Lease Liability</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_FinanceLeasesAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Finance Leases:</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_FinanceLeasesAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Finance Leases [Abstract]</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_FinanceLeasesOtherAssetsNoncurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Other noncurrent assets</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_FinanceLeasesOtherAssetsNoncurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Finance Leases Other Assets Noncurrent</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FinanceLeaseLiabilityCurrent" xlink:type="locator" xlink:label="us-gaap_FinanceLeaseLiabilityCurrent" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_FinanceLeaseLiabilityCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Accrued expenses and other current liabilities</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FinanceLeaseLiabilityCurrent" xlink:to="us-gaap_FinanceLeaseLiabilityCurrent_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_FinanceLeaseLiabilityCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Finance Lease Liability Current</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FinanceLeaseLiabilityCurrentStatementOfFinancialPositionExtensibleList" xlink:type="locator" xlink:label="us-gaap_FinanceLeaseLiabilityCurrentStatementOfFinancialPositionExtensibleList" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_FinanceLeaseLiabilityCurrentStatementOfFinancialPositionExtensibleList_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Finance Lease, Liability, Current, Statement of Financial Position [Extensible List]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FinanceLeaseLiabilityCurrentStatementOfFinancialPositionExtensibleList" xlink:to="us-gaap_FinanceLeaseLiabilityCurrentStatementOfFinancialPositionExtensibleList_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_FinanceLeaseLiabilityCurrentStatementOfFinancialPositionExtensibleList_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Finance Lease Liability Current Statement Of Financial Position Extensible List</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FinanceLeaseLiabilityNoncurrent" xlink:type="locator" xlink:label="us-gaap_FinanceLeaseLiabilityNoncurrent" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_FinanceLeaseLiabilityNoncurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Other long-term liabilities</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FinanceLeaseLiabilityNoncurrent" xlink:to="us-gaap_FinanceLeaseLiabilityNoncurrent_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_FinanceLeaseLiabilityNoncurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Finance Lease Liability Noncurrent</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FinanceLeaseLiabilityNoncurrentStatementOfFinancialPositionExtensibleList" xlink:type="locator" xlink:label="us-gaap_FinanceLeaseLiabilityNoncurrentStatementOfFinancialPositionExtensibleList" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_FinanceLeaseLiabilityNoncurrentStatementOfFinancialPositionExtensibleList_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Finance Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FinanceLeaseLiabilityNoncurrentStatementOfFinancialPositionExtensibleList" xlink:to="us-gaap_FinanceLeaseLiabilityNoncurrentStatementOfFinancialPositionExtensibleList_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_FinanceLeaseLiabilityNoncurrentStatementOfFinancialPositionExtensibleList_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Finance Lease Liability Noncurrent Statement Of Financial Position Extensible List</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_WeightedAverageRemainingLeaseTermAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Weighted Average Remaining Lease Term:</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_WeightedAverageRemainingLeaseTermAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Weighted Average Remaining Lease Term [Abstract]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OperatingLeaseWeightedAverageRemainingLeaseTerm1" xlink:type="locator" xlink:label="us-gaap_OperatingLeaseWeightedAverageRemainingLeaseTerm1" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_OperatingLeaseWeightedAverageRemainingLeaseTerm1_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Operating leases</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OperatingLeaseWeightedAverageRemainingLeaseTerm1" xlink:to="us-gaap_OperatingLeaseWeightedAverageRemainingLeaseTerm1_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_OperatingLeaseWeightedAverageRemainingLeaseTerm1_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Operating Lease Weighted Average Remaining Lease Term1</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FinanceLeaseWeightedAverageRemainingLeaseTerm1" xlink:type="locator" xlink:label="us-gaap_FinanceLeaseWeightedAverageRemainingLeaseTerm1" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_FinanceLeaseWeightedAverageRemainingLeaseTerm1_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Finance leases</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FinanceLeaseWeightedAverageRemainingLeaseTerm1" xlink:to="us-gaap_FinanceLeaseWeightedAverageRemainingLeaseTerm1_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_FinanceLeaseWeightedAverageRemainingLeaseTerm1_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Finance Lease Weighted Average Remaining Lease Term1</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_WeightedAverageDiscountRateAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Weighted Average Discount Rate:</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_WeightedAverageDiscountRateAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Weighted Average Discount Rate [Abstract]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OperatingLeaseWeightedAverageDiscountRatePercent" xlink:type="locator" xlink:label="us-gaap_OperatingLeaseWeightedAverageDiscountRatePercent" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_OperatingLeaseWeightedAverageDiscountRatePercent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Operating leases</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OperatingLeaseWeightedAverageDiscountRatePercent" xlink:to="us-gaap_OperatingLeaseWeightedAverageDiscountRatePercent_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_OperatingLeaseWeightedAverageDiscountRatePercent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Operating Lease Weighted Average Discount Rate Percent</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FinanceLeaseWeightedAverageDiscountRatePercent" xlink:type="locator" xlink:label="us-gaap_FinanceLeaseWeightedAverageDiscountRatePercent" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_FinanceLeaseWeightedAverageDiscountRatePercent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Finance leases</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FinanceLeaseWeightedAverageDiscountRatePercent" xlink:to="us-gaap_FinanceLeaseWeightedAverageDiscountRatePercent_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_FinanceLeaseWeightedAverageDiscountRatePercent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Finance Lease Weighted Average Discount Rate Percent</link:label>
    <link:loc xlink:href="psn-20191231.xsd#psn_OperatingLeaseNotYetCommencedExpense" xlink:type="locator" xlink:label="psn_OperatingLeaseNotYetCommencedExpense" />
    <link:label xml:lang="en-US" xlink:label="psn_OperatingLeaseNotYetCommencedExpense_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Operating lease not yet commenced expense.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="psn_OperatingLeaseNotYetCommencedExpense" xlink:to="psn_OperatingLeaseNotYetCommencedExpense_lbl" />
    <link:label xml:lang="en-US" xlink:label="psn_OperatingLeaseNotYetCommencedExpense_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Operating lease not yet commenced expense</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_OperatingLeaseNotYetCommencedExpense_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Operating Lease Not Yet Commenced Expense</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LesseeOperatingLeaseLeaseNotYetCommencedTermOfContract1" xlink:type="locator" xlink:label="us-gaap_LesseeOperatingLeaseLeaseNotYetCommencedTermOfContract1" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LesseeOperatingLeaseLeaseNotYetCommencedTermOfContract1_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Operating lease not yet commenced term of contract</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LesseeOperatingLeaseLeaseNotYetCommencedTermOfContract1" xlink:to="us-gaap_LesseeOperatingLeaseLeaseNotYetCommencedTermOfContract1_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LesseeOperatingLeaseLeaseNotYetCommencedTermOfContract1_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Lessee Operating Lease Lease Not Yet Commenced Term Of Contract1</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OperatingLeaseLiabilitiesPaymentsDueAbstract" xlink:type="locator" xlink:label="us-gaap_OperatingLeaseLiabilitiesPaymentsDueAbstract" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_OperatingLeaseLiabilitiesPaymentsDueAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Operating Leases</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OperatingLeaseLiabilitiesPaymentsDueAbstract" xlink:to="us-gaap_OperatingLeaseLiabilitiesPaymentsDueAbstract_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_OperatingLeaseLiabilitiesPaymentsDueAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Operating Lease Liabilities Payments Due [Abstract]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths" xlink:type="locator" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">2020</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths" xlink:to="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Lessee Operating Lease Liability Payments Due Next Twelve Months</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearTwo" xlink:type="locator" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearTwo" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearTwo_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">2021</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearTwo" xlink:to="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearTwo_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearTwo_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Lessee Operating Lease Liability Payments Due Year Two</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearThree" xlink:type="locator" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearThree" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearThree_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">2022</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearThree" xlink:to="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearThree_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearThree_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Lessee Operating Lease Liability Payments Due Year Three</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFour" xlink:type="locator" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFour" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFour_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">2023</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFour" xlink:to="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFour_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFour_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Lessee Operating Lease Liability Payments Due Year Four</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFive" xlink:type="locator" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFive" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFive_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">2024</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFive" xlink:to="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFive_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFive_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Lessee Operating Lease Liability Payments Due Year Five</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive" xlink:type="locator" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Thereafter</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive" xlink:to="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Lessee Operating Lease Liability Payments Due After Year Five</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue" xlink:type="locator" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Total lease payments</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue" xlink:to="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Lessee Operating Lease Liability Payments Due</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LesseeOperatingLeaseLiabilityUndiscountedExcessAmount" xlink:type="locator" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityUndiscountedExcessAmount" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityUndiscountedExcessAmount_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Less: imputed interest</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LesseeOperatingLeaseLiabilityUndiscountedExcessAmount" xlink:to="us-gaap_LesseeOperatingLeaseLiabilityUndiscountedExcessAmount_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityUndiscountedExcessAmount_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Lessee Operating Lease Liability Undiscounted Excess Amount</link:label>
    <link:label xml:lang="en-US" xlink:label="us-gaap_OperatingLeaseLiability_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Total present value of lease liabilities</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FinanceLeaseLiabilitiesPaymentsDueAbstract" xlink:type="locator" xlink:label="us-gaap_FinanceLeaseLiabilitiesPaymentsDueAbstract" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_FinanceLeaseLiabilitiesPaymentsDueAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Finance Leases</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FinanceLeaseLiabilitiesPaymentsDueAbstract" xlink:to="us-gaap_FinanceLeaseLiabilitiesPaymentsDueAbstract_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_FinanceLeaseLiabilitiesPaymentsDueAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Finance Lease Liabilities Payments Due [Abstract]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FinanceLeaseLiabilityPaymentsDueNextTwelveMonths" xlink:type="locator" xlink:label="us-gaap_FinanceLeaseLiabilityPaymentsDueNextTwelveMonths" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_FinanceLeaseLiabilityPaymentsDueNextTwelveMonths_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">2020</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FinanceLeaseLiabilityPaymentsDueNextTwelveMonths" xlink:to="us-gaap_FinanceLeaseLiabilityPaymentsDueNextTwelveMonths_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_FinanceLeaseLiabilityPaymentsDueNextTwelveMonths_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Finance Lease Liability Payments Due Next Twelve Months</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FinanceLeaseLiabilityPaymentsDueYearTwo" xlink:type="locator" xlink:label="us-gaap_FinanceLeaseLiabilityPaymentsDueYearTwo" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_FinanceLeaseLiabilityPaymentsDueYearTwo_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">2021</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FinanceLeaseLiabilityPaymentsDueYearTwo" xlink:to="us-gaap_FinanceLeaseLiabilityPaymentsDueYearTwo_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_FinanceLeaseLiabilityPaymentsDueYearTwo_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Finance Lease Liability Payments Due Year Two</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FinanceLeaseLiabilityPaymentsDueYearThree" xlink:type="locator" xlink:label="us-gaap_FinanceLeaseLiabilityPaymentsDueYearThree" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_FinanceLeaseLiabilityPaymentsDueYearThree_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">2022</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FinanceLeaseLiabilityPaymentsDueYearThree" xlink:to="us-gaap_FinanceLeaseLiabilityPaymentsDueYearThree_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_FinanceLeaseLiabilityPaymentsDueYearThree_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Finance Lease Liability Payments Due Year Three</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FinanceLeaseLiabilityPaymentsDueYearFour" xlink:type="locator" xlink:label="us-gaap_FinanceLeaseLiabilityPaymentsDueYearFour" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_FinanceLeaseLiabilityPaymentsDueYearFour_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">2023</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FinanceLeaseLiabilityPaymentsDueYearFour" xlink:to="us-gaap_FinanceLeaseLiabilityPaymentsDueYearFour_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_FinanceLeaseLiabilityPaymentsDueYearFour_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Finance Lease Liability Payments Due Year Four</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FinanceLeaseLiabilityPaymentsDueYearFive" xlink:type="locator" xlink:label="us-gaap_FinanceLeaseLiabilityPaymentsDueYearFive" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_FinanceLeaseLiabilityPaymentsDueYearFive_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">2024</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FinanceLeaseLiabilityPaymentsDueYearFive" xlink:to="us-gaap_FinanceLeaseLiabilityPaymentsDueYearFive_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_FinanceLeaseLiabilityPaymentsDueYearFive_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Finance Lease Liability Payments Due Year Five</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FinanceLeaseLiabilityPaymentsDueAfterYearFive" xlink:type="locator" xlink:label="us-gaap_FinanceLeaseLiabilityPaymentsDueAfterYearFive" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_FinanceLeaseLiabilityPaymentsDueAfterYearFive_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Thereafter</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FinanceLeaseLiabilityPaymentsDueAfterYearFive" xlink:to="us-gaap_FinanceLeaseLiabilityPaymentsDueAfterYearFive_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_FinanceLeaseLiabilityPaymentsDueAfterYearFive_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Finance Lease Liability Payments Due After Year Five</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FinanceLeaseLiabilityPaymentsDue" xlink:type="locator" xlink:label="us-gaap_FinanceLeaseLiabilityPaymentsDue" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_FinanceLeaseLiabilityPaymentsDue_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Total lease payments</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FinanceLeaseLiabilityPaymentsDue" xlink:to="us-gaap_FinanceLeaseLiabilityPaymentsDue_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_FinanceLeaseLiabilityPaymentsDue_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Finance Lease Liability Payments Due</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FinanceLeaseLiabilityUndiscountedExcessAmount" xlink:type="locator" xlink:label="us-gaap_FinanceLeaseLiabilityUndiscountedExcessAmount" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_FinanceLeaseLiabilityUndiscountedExcessAmount_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Less: imputed interest</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FinanceLeaseLiabilityUndiscountedExcessAmount" xlink:to="us-gaap_FinanceLeaseLiabilityUndiscountedExcessAmount_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_FinanceLeaseLiabilityUndiscountedExcessAmount_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Finance Lease Liability Undiscounted Excess Amount</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FinanceLeaseLiability" xlink:type="locator" xlink:label="us-gaap_FinanceLeaseLiability" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_FinanceLeaseLiability_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Total present value of lease liabilities</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FinanceLeaseLiability" xlink:to="us-gaap_FinanceLeaseLiability_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_FinanceLeaseLiability_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Finance Lease Liability</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OperatingLeaseExpense" xlink:type="locator" xlink:label="us-gaap_OperatingLeaseExpense" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_OperatingLeaseExpense_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Rental expense</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OperatingLeaseExpense" xlink:to="us-gaap_OperatingLeaseExpense_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_OperatingLeaseExpense_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Operating Lease Expense</link:label>
    <link:loc xlink:href="psn-20191231.xsd#psn_EmployeeServiceShareBasedCompensationTaxBenefitRealizedFromVestingOfAwards" xlink:type="locator" xlink:label="psn_EmployeeServiceShareBasedCompensationTaxBenefitRealizedFromVestingOfAwards" />
    <link:label xml:lang="en-US" xlink:label="psn_EmployeeServiceShareBasedCompensationTaxBenefitRealizedFromVestingOfAwards_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Employee service share based compensation tax benefit realized from vesting of awards.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="psn_EmployeeServiceShareBasedCompensationTaxBenefitRealizedFromVestingOfAwards" xlink:to="psn_EmployeeServiceShareBasedCompensationTaxBenefitRealizedFromVestingOfAwards_lbl" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:type="locator" xlink:label="us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Schedule Of Share Based Compensation Arrangements By Share Based Payment Award [Table]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:to="us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Schedule Of Share Based Compensation Arrangements By Share Based Payment Award [Table]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Share Based Compensation Arrangement By Share Based Payment Award [Line Items]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Share Based Compensation Arrangement By Share Based Payment Award [Line Items]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AllocatedShareBasedCompensationExpenseNetOfTax" xlink:type="locator" xlink:label="us-gaap_AllocatedShareBasedCompensationExpenseNetOfTax" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_AllocatedShareBasedCompensationExpenseNetOfTax_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel">Stock-based compensation expense, net of tax benefits</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AllocatedShareBasedCompensationExpenseNetOfTax" xlink:to="us-gaap_AllocatedShareBasedCompensationExpenseNetOfTax_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_AllocatedShareBasedCompensationExpenseNetOfTax_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Allocated Share Based Compensation Expense Net Of Tax</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense" xlink:type="locator" xlink:label="us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Stock-based compensation expense, tax benefits</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense" xlink:to="us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Employee Service Share Based Compensation Tax Benefit From Compensation Expense</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_EmployeeServiceShareBasedCompensationTaxBenefitRealizedFromVestingOfAwards_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Stock-based compensation expense, tax benefit realized related to awards vested</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_EmployeeServiceShareBasedCompensationTaxBenefitRealizedFromVestingOfAwards_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Employee Service Share Based Compensation Tax Benefit Realized From Vesting Of Awards</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized" xlink:type="locator" xlink:label="us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Compensation cost related to non-vested awards not yet recognized</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized" xlink:to="us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Employee Service Share Based Compensation Nonvested Awards Total Compensation Cost Not Yet Recognized</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1" xlink:type="locator" xlink:label="us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Unrecognized compensation costs recognized period</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1" xlink:to="us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Employee Service Share Based Compensation Nonvested Awards Total Compensation Cost Not Yet Recognized Period For Recognition1</link:label>
    <link:loc xlink:href="psn-20191231.xsd#psn_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfYearsOverWhichSharePriceIncrease" xlink:type="locator" xlink:label="psn_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfYearsOverWhichSharePriceIncrease" />
    <link:label xml:lang="en-US" xlink:label="psn_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfYearsOverWhichSharePriceIncrease_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Share based compensation arrangement by share based payment award number of years over which share price increase.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="psn_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfYearsOverWhichSharePriceIncrease" xlink:to="psn_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfYearsOverWhichSharePriceIncrease_lbl" />
    <link:label xml:lang="en-US" xlink:label="psn_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfYearsOverWhichSharePriceIncrease_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Number of years over which share price increase</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfYearsOverWhichSharePriceIncrease_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Share Based Compensation Arrangement By Share Based Payment Award Number Of Years Over Which Share Price Increase</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Vesting period</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Share Based Compensation Arrangement By Share Based Payment Award Award Vesting Period1</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Dividend yield</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Expected Dividend Rate</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Expected volatility</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Expected Volatility Rate</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Risk-free interest rate</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Risk Free Interest Rate</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1" xlink:type="locator" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Expected term</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1" xlink:to="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Sharebased Compensation Arrangement By Sharebased Payment Award Fair Value Assumptions Expected Term1</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/periodStartLabel">Number of Units, Unvested, Beginning balance</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Number</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod" />
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    <link:label xml:lang="en-US" xlink:label="us-gaap_ScheduleOfAcquiredFiniteLivedIntangibleAssetByMajorClassTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Schedule Of Acquired Finite Lived Intangible Asset By Major Class [Table]</link:label>
    <link:label xml:lang="en-US" xlink:label="us-gaap_InProcessResearchAndDevelopmentMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel">In Process Research and Development</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OtherIntangibleAssetsMember" xlink:type="locator" xlink:label="us-gaap_OtherIntangibleAssetsMember" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_OtherIntangibleAssetsMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Other Intangibles</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OtherIntangibleAssetsMember" xlink:to="us-gaap_OtherIntangibleAssetsMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_OtherIntangibleAssetsMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Other Intangible Assets [Member]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsGross" xlink:type="locator" xlink:label="us-gaap_FiniteLivedIntangibleAssetsGross" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_FiniteLivedIntangibleAssetsGross_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Gross Carrying Amount</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FiniteLivedIntangibleAssetsGross" xlink:to="us-gaap_FiniteLivedIntangibleAssetsGross_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_FiniteLivedIntangibleAssetsGross_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Finite Lived Intangible Assets Gross</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization" xlink:type="locator" xlink:label="us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Accumulated Amortization</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization" xlink:to="us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Finite Lived Intangible Assets Accumulated Amortization</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsNet" xlink:type="locator" xlink:label="us-gaap_FiniteLivedIntangibleAssetsNet" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_FiniteLivedIntangibleAssetsNet_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Net Carrying Amount</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FiniteLivedIntangibleAssetsNet" xlink:to="us-gaap_FiniteLivedIntangibleAssetsNet_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_FiniteLivedIntangibleAssetsNet_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Finite Lived Intangible Assets Net</link:label>
    <link:label xml:lang="en-US" xlink:label="us-gaap_AmortizationOfIntangibleAssets_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel">Amortization expense of intangible assets</link:label>
    <link:loc xlink:href="psn-20191231.xsd#psn_FiniteLivedIntangibleAssetsAmortizableAmount" xlink:type="locator" xlink:label="psn_FiniteLivedIntangibleAssetsAmortizableAmount" />
    <link:label xml:lang="en-US" xlink:label="psn_FiniteLivedIntangibleAssetsAmortizableAmount_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Finite lived intangible assets amortizable amount.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="psn_FiniteLivedIntangibleAssetsAmortizableAmount" xlink:to="psn_FiniteLivedIntangibleAssetsAmortizableAmount_lbl" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths" xlink:type="locator" xlink:label="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">2020</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths" xlink:to="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Finite Lived Intangible Assets Amortization Expense Next Twelve Months</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo" xlink:type="locator" xlink:label="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">2021</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo" xlink:to="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Finite Lived Intangible Assets Amortization Expense Year Two</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearThree" xlink:type="locator" xlink:label="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearThree" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearThree_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">2022</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearThree" xlink:to="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearThree_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearThree_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Finite Lived Intangible Assets Amortization Expense Year Three</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFour" xlink:type="locator" xlink:label="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFour" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFour_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">2023</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFour" xlink:to="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFour_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFour_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Finite Lived Intangible Assets Amortization Expense Year Four</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFive" xlink:type="locator" xlink:label="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFive" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFive_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">2024</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFive" xlink:to="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFive_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFive_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Finite Lived Intangible Assets Amortization Expense Year Five</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseAfterYearFive" xlink:type="locator" xlink:label="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseAfterYearFive" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseAfterYearFive_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Thereafter</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseAfterYearFive_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Finite Lived Intangible Assets Amortization Expense After Year Five</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_FiniteLivedIntangibleAssetsAmortizableAmount_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Finite-Lived Intangible Assets, Net</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_FiniteLivedIntangibleAssetsAmortizableAmount_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Finite Lived Intangible Assets Amortizable Amount</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ScheduleOfPropertyPlantAndEquipmentTable" xlink:type="locator" xlink:label="us-gaap_ScheduleOfPropertyPlantAndEquipmentTable" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Schedule Of Property Plant And Equipment [Table]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ScheduleOfPropertyPlantAndEquipmentTable" xlink:to="us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Schedule Of Property Plant And Equipment [Table]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis" xlink:type="locator" xlink:label="us-gaap_PropertyPlantAndEquipmentByTypeAxis" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_PropertyPlantAndEquipmentByTypeAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Property, Plant and Equipment, Type</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_PropertyPlantAndEquipmentByTypeAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Property Plant And Equipment By Type [Axis]</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_PropertyPlantAndEquipmentTypeDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Property, Plant and Equipment, Type</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_PropertyPlantAndEquipmentTypeDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Property Plant And Equipment Type [Domain]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BuildingAndBuildingImprovementsMember" xlink:type="locator" xlink:label="us-gaap_BuildingAndBuildingImprovementsMember" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_BuildingAndBuildingImprovementsMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Buildings and Leasehold Improvements</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_BuildingAndBuildingImprovementsMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Building And Building Improvements [Member]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FurnitureAndFixturesMember" xlink:type="locator" xlink:label="us-gaap_FurnitureAndFixturesMember" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_FurnitureAndFixturesMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Furniture and Equipment</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_FurnitureAndFixturesMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Furniture And Fixtures [Member]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ComputerEquipmentMember" xlink:type="locator" xlink:label="us-gaap_ComputerEquipmentMember" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ComputerEquipmentMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Computer Systems and Equipment</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ComputerEquipmentMember" xlink:to="us-gaap_ComputerEquipmentMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ComputerEquipmentMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Computer Equipment [Member]</link:label>
    <link:loc xlink:href="psn-20191231.xsd#psn_ConstructionEquipmentMember" xlink:type="locator" xlink:label="psn_ConstructionEquipmentMember" />
    <link:label xml:lang="en-US" xlink:label="psn_ConstructionEquipmentMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Construction equipment.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="psn_ConstructionEquipmentMember" xlink:to="psn_ConstructionEquipmentMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="psn_ConstructionEquipmentMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Construction Equipment</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_ConstructionEquipmentMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Construction Equipment [Member]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PropertyPlantAndEquipmentLineItems" xlink:type="locator" xlink:label="us-gaap_PropertyPlantAndEquipmentLineItems" />
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    <link:label xml:lang="en-US" xlink:label="us-gaap_PropertyPlantAndEquipmentLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Property Plant And Equipment [Line Items]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PropertyPlantAndEquipmentGross" xlink:type="locator" xlink:label="us-gaap_PropertyPlantAndEquipmentGross" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_PropertyPlantAndEquipmentGross_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Property and equipment, gross</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_PropertyPlantAndEquipmentGross_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Property Plant And Equipment Gross</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment" xlink:type="locator" xlink:label="us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment" />
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    <link:label xml:lang="en-US" xlink:label="us-gaap_PropertyPlantAndEquipmentNet_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Property and equipment, net</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PropertyPlantAndEquipmentUsefulLife" xlink:type="locator" xlink:label="us-gaap_PropertyPlantAndEquipmentUsefulLife" />
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    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PropertyPlantAndEquipmentUsefulLife" xlink:to="us-gaap_PropertyPlantAndEquipmentUsefulLife_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_PropertyPlantAndEquipmentUsefulLife_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Property Plant And Equipment Useful Life</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_Depreciation" xlink:type="locator" xlink:label="us-gaap_Depreciation" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_Depreciation_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Depreciation expense</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_Depreciation" xlink:to="us-gaap_Depreciation_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_Depreciation_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Depreciation</link:label>
    <link:loc xlink:href="psn-20191231.xsd#psn_NumberOfSaleLeasebackTransactionsConsummated" xlink:type="locator" xlink:label="psn_NumberOfSaleLeasebackTransactionsConsummated" />
    <link:label xml:lang="en-US" xlink:label="psn_NumberOfSaleLeasebackTransactionsConsummated_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Number of sale leaseback transactions consummated.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="psn_NumberOfSaleLeasebackTransactionsConsummated" xlink:to="psn_NumberOfSaleLeasebackTransactionsConsummated_lbl" />
    <link:loc xlink:href="psn-20191231.xsd#psn_NumberOfOfficeBuildingsSold" xlink:type="locator" xlink:label="psn_NumberOfOfficeBuildingsSold" />
    <link:label xml:lang="en-US" xlink:label="psn_NumberOfOfficeBuildingsSold_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Number of office buildings sold.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="psn_NumberOfOfficeBuildingsSold" xlink:to="psn_NumberOfOfficeBuildingsSold_lbl" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_SaleLeasebackTransactionTable" xlink:type="locator" xlink:label="us-gaap_SaleLeasebackTransactionTable" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_SaleLeasebackTransactionTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Sale Leaseback Transaction [Table]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SaleLeasebackTransactionTable" xlink:to="us-gaap_SaleLeasebackTransactionTable_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_SaleLeasebackTransactionTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Sale Leaseback Transaction [Table]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_SaleLeasebackTransactionLineItems" xlink:type="locator" xlink:label="us-gaap_SaleLeasebackTransactionLineItems" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_SaleLeasebackTransactionLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Sale Leaseback Transaction [Line Items]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SaleLeasebackTransactionLineItems" xlink:to="us-gaap_SaleLeasebackTransactionLineItems_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_SaleLeasebackTransactionLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Sale Leaseback Transaction [Line Items]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_SaleLeasebackTransactionDescriptionOfAssetS" xlink:type="locator" xlink:label="us-gaap_SaleLeasebackTransactionDescriptionOfAssetS" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_SaleLeasebackTransactionDescriptionOfAssetS_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Sale leaseback transaction, description</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SaleLeasebackTransactionDescriptionOfAssetS" xlink:to="us-gaap_SaleLeasebackTransactionDescriptionOfAssetS_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_SaleLeasebackTransactionDescriptionOfAssetS_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Sale Leaseback Transaction Description Of Asset S</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_NumberOfSaleLeasebackTransactionsConsummated_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Number of sale leaseback transactions consummated</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_NumberOfSaleLeasebackTransactionsConsummated_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Number Of Sale Leaseback Transactions Consummated</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_NumberOfOfficeBuildingsSold_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Number of sale leaseback transaction associated with sale</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_NumberOfOfficeBuildingsSold_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Number Of Office Buildings Sold</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_SaleAndLeasebackTransactionGainLossNet" xlink:type="locator" xlink:label="us-gaap_SaleAndLeasebackTransactionGainLossNet" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_SaleAndLeasebackTransactionGainLossNet_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Gain recognized to the sale leaseback transaction</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SaleAndLeasebackTransactionGainLossNet" xlink:to="us-gaap_SaleAndLeasebackTransactionGainLossNet_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_SaleAndLeasebackTransactionGainLossNet_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Sale And Leaseback Transaction Gain Loss Net</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_SaleLeasebackTransactionAmortizationOfDeferredGain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Amortization of deferred gain</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_SaleLeasebackTransactionAmortizationOfDeferredGain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Sale Leaseback Transaction Amortization Of Deferred Gain</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_NewAccountingPronouncementOrChangeInAccountingPrincipleCumulativeEffectOfChangeOnEquityOrNetAssets1" xlink:type="locator" xlink:label="us-gaap_NewAccountingPronouncementOrChangeInAccountingPrincipleCumulativeEffectOfChangeOnEquityOrNetAssets1" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_NewAccountingPronouncementOrChangeInAccountingPrincipleCumulativeEffectOfChangeOnEquityOrNetAssets1_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Deferred gain balance recognized</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_NewAccountingPronouncementOrChangeInAccountingPrincipleCumulativeEffectOfChangeOnEquityOrNetAssets1" xlink:to="us-gaap_NewAccountingPronouncementOrChangeInAccountingPrincipleCumulativeEffectOfChangeOnEquityOrNetAssets1_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_NewAccountingPronouncementOrChangeInAccountingPrincipleCumulativeEffectOfChangeOnEquityOrNetAssets1_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">New Accounting Pronouncement Or Change In Accounting Principle Cumulative Effect Of Change On Equity Or Net Assets1</link:label>
    <link:loc xlink:href="psn-20191231.xsd#psn_ProjectCostAccrualsCurrent" xlink:type="locator" xlink:label="psn_ProjectCostAccrualsCurrent" />
    <link:label xml:lang="en-US" xlink:label="psn_ProjectCostAccrualsCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Project cost accruals current.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="psn_ProjectCostAccrualsCurrent" xlink:to="psn_ProjectCostAccrualsCurrent_lbl" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AccruedSalariesCurrent" xlink:type="locator" xlink:label="us-gaap_AccruedSalariesCurrent" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_AccruedSalariesCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Salaries and wages</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AccruedSalariesCurrent" xlink:to="us-gaap_AccruedSalariesCurrent_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_AccruedSalariesCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Accrued Salaries Current</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AccruedEmployeeBenefitsCurrent" xlink:type="locator" xlink:label="us-gaap_AccruedEmployeeBenefitsCurrent" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_AccruedEmployeeBenefitsCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Employee benefits</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AccruedEmployeeBenefitsCurrent" xlink:to="us-gaap_AccruedEmployeeBenefitsCurrent_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_AccruedEmployeeBenefitsCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Accrued Employee Benefits Current</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AccruedInsuranceCurrent" xlink:type="locator" xlink:label="us-gaap_AccruedInsuranceCurrent" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_AccruedInsuranceCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Self-insurance liability</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AccruedInsuranceCurrent" xlink:to="us-gaap_AccruedInsuranceCurrent_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_AccruedInsuranceCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Accrued Insurance Current</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_ProjectCostAccrualsCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Project cost accruals</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_ProjectCostAccrualsCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Project Cost Accruals Current</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OtherAccruedLiabilitiesCurrent" xlink:type="locator" xlink:label="us-gaap_OtherAccruedLiabilitiesCurrent" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_OtherAccruedLiabilitiesCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Other accrued expenses</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OtherAccruedLiabilitiesCurrent" xlink:to="us-gaap_OtherAccruedLiabilitiesCurrent_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_OtherAccruedLiabilitiesCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Other Accrued Liabilities Current</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_AccruedExpensesAndOtherCurrentLiabilities_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Total accrued expenses and other current liabilities</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtInstrumentTable" xlink:type="locator" xlink:label="us-gaap_DebtInstrumentTable" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DebtInstrumentTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Debt Instrument [Table]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DebtInstrumentTable" xlink:to="us-gaap_DebtInstrumentTable_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DebtInstrumentTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Debt Instrument [Table]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LongtermDebtTypeAxis" xlink:type="locator" xlink:label="us-gaap_LongtermDebtTypeAxis" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LongtermDebtTypeAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Long-term Debt, Type</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LongtermDebtTypeAxis" xlink:to="us-gaap_LongtermDebtTypeAxis_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LongtermDebtTypeAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Longterm Debt Type [Axis]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LongtermDebtTypeDomain" xlink:type="locator" xlink:label="us-gaap_LongtermDebtTypeDomain" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LongtermDebtTypeDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Long-term Debt, Type</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LongtermDebtTypeDomain" xlink:to="us-gaap_LongtermDebtTypeDomain_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LongtermDebtTypeDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Longterm Debt Type [Domain]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_SeniorNotesMember" xlink:type="locator" xlink:label="us-gaap_SeniorNotesMember" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_SeniorNotesMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Senior Notes</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SeniorNotesMember" xlink:to="us-gaap_SeniorNotesMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_SeniorNotesMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Senior Notes [Member]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtInstrumentLineItems" xlink:type="locator" xlink:label="us-gaap_DebtInstrumentLineItems" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DebtInstrumentLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Debt Instrument [Line Items]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_DebtInstrumentLineItems_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DebtInstrumentLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Debt Instrument [Line Items]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtInstrumentCarryingAmount" xlink:type="locator" xlink:label="us-gaap_DebtInstrumentCarryingAmount" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DebtInstrumentCarryingAmount_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Long-term debt</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DebtInstrumentCarryingAmount" xlink:to="us-gaap_DebtInstrumentCarryingAmount_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DebtInstrumentCarryingAmount_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Debt Instrument Carrying Amount</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DeferredFinanceCostsNoncurrentNet" xlink:type="locator" xlink:label="us-gaap_DeferredFinanceCostsNoncurrentNet" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DeferredFinanceCostsNoncurrentNet_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Long-Term Debt issuance costs</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DeferredFinanceCostsNoncurrentNet" xlink:to="us-gaap_DeferredFinanceCostsNoncurrentNet_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DeferredFinanceCostsNoncurrentNet_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Deferred Finance Costs Noncurrent Net</link:label>
    <link:label xml:lang="en-US" xlink:label="us-gaap_LongTermDebt_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Long-term debt</link:label>
    <link:loc xlink:href="psn-20191231.xsd#psn_LineOfCreditFacilityExtendedDate" xlink:type="locator" xlink:label="psn_LineOfCreditFacilityExtendedDate" />
    <link:label xml:lang="en-US" xlink:label="psn_LineOfCreditFacilityExtendedDate_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Line of credit facility extended date.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="psn_LineOfCreditFacilityExtendedDate" xlink:to="psn_LineOfCreditFacilityExtendedDate_lbl" />
    <link:loc xlink:href="psn-20191231.xsd#psn_CreditAgreementMember" xlink:type="locator" xlink:label="psn_CreditAgreementMember" />
    <link:label xml:lang="en-US" xlink:label="psn_CreditAgreementMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Credit agreement.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="psn_CreditAgreementMember" xlink:to="psn_CreditAgreementMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="psn_CreditAgreementMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Credit Agreement</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_CreditAgreementMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Credit Agreement [Member]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_VariableRateAxis" xlink:type="locator" xlink:label="us-gaap_VariableRateAxis" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_VariableRateAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Variable Rate</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_VariableRateAxis" xlink:to="us-gaap_VariableRateAxis_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_VariableRateAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Variable Rate [Axis]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_VariableRateDomain" xlink:type="locator" xlink:label="us-gaap_VariableRateDomain" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_VariableRateDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Variable Rate</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_VariableRateDomain" xlink:to="us-gaap_VariableRateDomain_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_VariableRateDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Variable Rate [Domain]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BaseRateMember" xlink:type="locator" xlink:label="us-gaap_BaseRateMember" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_BaseRateMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Base Rate</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_BaseRateMember" xlink:to="us-gaap_BaseRateMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_BaseRateMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Base Rate [Member]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LondonInterbankOfferedRateLIBORMember" xlink:type="locator" xlink:label="us-gaap_LondonInterbankOfferedRateLIBORMember" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LondonInterbankOfferedRateLIBORMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">LIBOR</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LondonInterbankOfferedRateLIBORMember" xlink:to="us-gaap_LondonInterbankOfferedRateLIBORMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LondonInterbankOfferedRateLIBORMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">London Interbank Offered Rate L I B O R [Member]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PrivatePlacementMember" xlink:type="locator" xlink:label="us-gaap_PrivatePlacementMember" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_PrivatePlacementMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Private Placement</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PrivatePlacementMember" xlink:to="us-gaap_PrivatePlacementMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_PrivatePlacementMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Private Placement [Member]</link:label>
    <link:loc xlink:href="psn-20191231.xsd#psn_AccruedExpensesAndOtherCurrentLiabilitiesMember" xlink:type="locator" xlink:label="psn_AccruedExpensesAndOtherCurrentLiabilitiesMember" />
    <link:label xml:lang="en-US" xlink:label="psn_AccruedExpensesAndOtherCurrentLiabilitiesMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Accrued expenses and other current liabilities.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="psn_AccruedExpensesAndOtherCurrentLiabilitiesMember" xlink:to="psn_AccruedExpensesAndOtherCurrentLiabilitiesMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="psn_AccruedExpensesAndOtherCurrentLiabilitiesMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Accrued Expenses and Other Current Liabilities</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_AccruedExpensesAndOtherCurrentLiabilitiesMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Accrued Expenses And Other Current Liabilities [Member]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LineOfCreditFacilityInitiationDate1" xlink:type="locator" xlink:label="us-gaap_LineOfCreditFacilityInitiationDate1" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LineOfCreditFacilityInitiationDate1_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Amended and restated credit agreement date</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LineOfCreditFacilityInitiationDate1" xlink:to="us-gaap_LineOfCreditFacilityInitiationDate1_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LineOfCreditFacilityInitiationDate1_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Line Of Credit Facility Initiation Date1</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DeferredFinanceCostsNet" xlink:type="locator" xlink:label="us-gaap_DeferredFinanceCostsNet" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DeferredFinanceCostsNet_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Debt issuance costs incurred</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DeferredFinanceCostsNet" xlink:to="us-gaap_DeferredFinanceCostsNet_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DeferredFinanceCostsNet_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Deferred Finance Costs Net</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LineOfCreditFacilityCurrentBorrowingCapacity" xlink:type="locator" xlink:label="us-gaap_LineOfCreditFacilityCurrentBorrowingCapacity" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LineOfCreditFacilityCurrentBorrowingCapacity_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Revolving credit facility</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LineOfCreditFacilityCurrentBorrowingCapacity" xlink:to="us-gaap_LineOfCreditFacilityCurrentBorrowingCapacity_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LineOfCreditFacilityCurrentBorrowingCapacity_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Line Of Credit Facility Current Borrowing Capacity</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity" xlink:type="locator" xlink:label="us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Increase in revolving credit facility</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity" xlink:to="us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Line Of Credit Facility Maximum Borrowing Capacity</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_LineOfCreditFacilityExtendedDate_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Credit agreement extended date</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_LineOfCreditFacilityExtendedDate_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Line Of Credit Facility Extended Date</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtInstrumentBasisSpreadOnVariableRate1" xlink:type="locator" xlink:label="us-gaap_DebtInstrumentBasisSpreadOnVariableRate1" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Margin interest rate</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DebtInstrumentBasisSpreadOnVariableRate1" xlink:to="us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Debt Instrument Basis Spread On Variable Rate1</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentage" xlink:type="locator" xlink:label="us-gaap_DebtInstrumentInterestRateStatedPercentage" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DebtInstrumentInterestRateStatedPercentage_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Interest rate</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DebtInstrumentInterestRateStatedPercentage" xlink:to="us-gaap_DebtInstrumentInterestRateStatedPercentage_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DebtInstrumentInterestRateStatedPercentage_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Debt Instrument Interest Rate Stated Percentage</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LettersOfCreditOutstandingAmount" xlink:type="locator" xlink:label="us-gaap_LettersOfCreditOutstandingAmount" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LettersOfCreditOutstandingAmount_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Letters of credit outstanding amount</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LettersOfCreditOutstandingAmount" xlink:to="us-gaap_LettersOfCreditOutstandingAmount_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LettersOfCreditOutstandingAmount_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Letters Of Credit Outstanding Amount</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_RepaymentsOfDebt" xlink:type="locator" xlink:label="us-gaap_RepaymentsOfDebt" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_RepaymentsOfDebt_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Repayment of outstanding balance</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_RepaymentsOfDebt" xlink:to="us-gaap_RepaymentsOfDebt_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_RepaymentsOfDebt_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Repayments Of Debt</link:label>
    <link:loc xlink:href="psn-20191231.xsd#psn_SeriesASeniorNoteMember" xlink:type="locator" xlink:label="psn_SeriesASeniorNoteMember" />
    <link:label xml:lang="en-US" xlink:label="psn_SeriesASeniorNoteMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Series A senior note.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="psn_SeriesASeniorNoteMember" xlink:to="psn_SeriesASeniorNoteMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="psn_SeriesASeniorNoteMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Senior Note, Series A</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_SeriesASeniorNoteMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Series A Senior Note [Member]</link:label>
    <link:loc xlink:href="psn-20191231.xsd#psn_SeriesBSeniorNoteMember" xlink:type="locator" xlink:label="psn_SeriesBSeniorNoteMember" />
    <link:label xml:lang="en-US" xlink:label="psn_SeriesBSeniorNoteMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Series B senior note.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="psn_SeriesBSeniorNoteMember" xlink:to="psn_SeriesBSeniorNoteMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="psn_SeriesBSeniorNoteMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Senior Note, Series B</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_SeriesBSeniorNoteMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Series B Senior Note [Member]</link:label>
    <link:loc xlink:href="psn-20191231.xsd#psn_SeriesCSeniorNoteMember" xlink:type="locator" xlink:label="psn_SeriesCSeniorNoteMember" />
    <link:label xml:lang="en-US" xlink:label="psn_SeriesCSeniorNoteMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Series C senior note.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="psn_SeriesCSeniorNoteMember" xlink:to="psn_SeriesCSeniorNoteMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="psn_SeriesCSeniorNoteMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Senior Note, Series C</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_SeriesCSeniorNoteMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Series C Senior Note [Member]</link:label>
    <link:loc xlink:href="psn-20191231.xsd#psn_SeriesDSeniorNoteMember" xlink:type="locator" xlink:label="psn_SeriesDSeniorNoteMember" />
    <link:label xml:lang="en-US" xlink:label="psn_SeriesDSeniorNoteMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Series D senior note.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="psn_SeriesDSeniorNoteMember" xlink:to="psn_SeriesDSeniorNoteMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="psn_SeriesDSeniorNoteMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Senior Note, Series D</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_SeriesDSeniorNoteMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Series D Senior Note [Member]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtInstrumentFaceAmount" xlink:type="locator" xlink:label="us-gaap_DebtInstrumentFaceAmount" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DebtInstrumentFaceAmount_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Debt Amount</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DebtInstrumentFaceAmount" xlink:to="us-gaap_DebtInstrumentFaceAmount_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DebtInstrumentFaceAmount_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Debt Instrument Face Amount</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtInstrumentMaturityDate" xlink:type="locator" xlink:label="us-gaap_DebtInstrumentMaturityDate" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DebtInstrumentMaturityDate_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Maturity Date</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DebtInstrumentMaturityDate" xlink:to="us-gaap_DebtInstrumentMaturityDate_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DebtInstrumentMaturityDate_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Debt Instrument Maturity Date</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtInstrumentInterestRateDuringPeriod" xlink:type="locator" xlink:label="us-gaap_DebtInstrumentInterestRateDuringPeriod" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DebtInstrumentInterestRateDuringPeriod_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Interest Rate</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DebtInstrumentInterestRateDuringPeriod" xlink:to="us-gaap_DebtInstrumentInterestRateDuringPeriod_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DebtInstrumentInterestRateDuringPeriod_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Debt Instrument Interest Rate During Period</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_InterestExpenseDebt" xlink:type="locator" xlink:label="us-gaap_InterestExpenseDebt" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_InterestExpenseDebt_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Interest expense</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_InterestExpenseDebt" xlink:to="us-gaap_InterestExpenseDebt_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_InterestExpenseDebt_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Interest Expense Debt</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtInstrumentPeriodicPayment" xlink:type="locator" xlink:label="us-gaap_DebtInstrumentPeriodicPayment" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DebtInstrumentPeriodicPayment_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Interest payments</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DebtInstrumentPeriodicPayment" xlink:to="us-gaap_DebtInstrumentPeriodicPayment_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DebtInstrumentPeriodicPayment_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Debt Instrument Periodic Payment</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_InterestPayableCurrent" xlink:type="locator" xlink:label="us-gaap_InterestPayableCurrent" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_InterestPayableCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Interest payable</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_InterestPayableCurrent" xlink:to="us-gaap_InterestPayableCurrent_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_InterestPayableCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Interest Payable Current</link:label>
    <link:label xml:lang="en-US" xlink:label="us-gaap_AmortizationOfFinancingCosts_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel">Amortization of debt issuance costs</link:label>
    <link:loc xlink:href="psn-20191231.xsd#psn_OtherLiabilitiesNoncurrent1" xlink:type="locator" xlink:label="psn_OtherLiabilitiesNoncurrent1" />
    <link:label xml:lang="en-US" xlink:label="psn_OtherLiabilitiesNoncurrent1_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Other liabilities noncurrent.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="psn_OtherLiabilitiesNoncurrent1" xlink:to="psn_OtherLiabilitiesNoncurrent1_lbl" />
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    <link:loc xlink:href="psn-20191231.xsd#psn_StateAndLocalJurisdictionAndForeignMember" xlink:type="locator" xlink:label="psn_StateAndLocalJurisdictionAndForeignMember" />
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    <link:loc xlink:href="psn-20191231.xsd#psn_EffectiveIncomeTaxRateReconciliationOtherPermanentItemsNet" xlink:type="locator" xlink:label="psn_EffectiveIncomeTaxRateReconciliationOtherPermanentItemsNet" />
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    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IncomeTaxReconciliationNondeductibleExpense" xlink:type="locator" xlink:label="us-gaap_IncomeTaxReconciliationNondeductibleExpense" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_IncomeTaxReconciliationNondeductibleExpense_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">S- corporation exclusion</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_IncomeTaxReconciliationNondeductibleExpense_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Income Tax Reconciliation Nondeductible Expense</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IncomeTaxReconciliationStateAndLocalIncomeTaxes" xlink:type="locator" xlink:label="us-gaap_IncomeTaxReconciliationStateAndLocalIncomeTaxes" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_IncomeTaxReconciliationStateAndLocalIncomeTaxes_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">State taxes, net of federal tax benefit</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_IncomeTaxReconciliationStateAndLocalIncomeTaxes_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Income Tax Reconciliation State And Local Income Taxes</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IncomeTaxReconciliationChangeInEnactedTaxRate" xlink:type="locator" xlink:label="us-gaap_IncomeTaxReconciliationChangeInEnactedTaxRate" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_IncomeTaxReconciliationChangeInEnactedTaxRate_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Change in tax status</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_IncomeTaxReconciliationChangeInEnactedTaxRate" xlink:to="us-gaap_IncomeTaxReconciliationChangeInEnactedTaxRate_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_IncomeTaxReconciliationChangeInEnactedTaxRate_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Income Tax Reconciliation Change In Enacted Tax Rate</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IncomeTaxReconciliationChangeInDeferredTaxAssetsValuationAllowance" xlink:type="locator" xlink:label="us-gaap_IncomeTaxReconciliationChangeInDeferredTaxAssetsValuationAllowance" />
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    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IncomeTaxReconciliationTaxContingencies" xlink:type="locator" xlink:label="us-gaap_IncomeTaxReconciliationTaxContingencies" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_IncomeTaxReconciliationTaxContingencies_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Change in uncertain tax positions</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_IncomeTaxReconciliationTaxContingencies" xlink:to="us-gaap_IncomeTaxReconciliationTaxContingencies_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_IncomeTaxReconciliationTaxContingencies_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Income Tax Reconciliation Tax Contingencies</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IncomeTaxReconciliationForeignIncomeTaxRateDifferential" xlink:type="locator" xlink:label="us-gaap_IncomeTaxReconciliationForeignIncomeTaxRateDifferential" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_IncomeTaxReconciliationForeignIncomeTaxRateDifferential_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Foreign tax rate differential</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_IncomeTaxReconciliationForeignIncomeTaxRateDifferential_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Income Tax Reconciliation Foreign Income Tax Rate Differential</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IncomeTaxReconciliationTaxCreditsForeign" xlink:type="locator" xlink:label="us-gaap_IncomeTaxReconciliationTaxCreditsForeign" />
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    <link:label xml:lang="en-US" xlink:label="psn_IncomeTaxReconciliationTransactionCosts_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Transaction costs</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_IncomeTaxReconciliationTransactionCosts_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Income Tax Reconciliation Transaction Costs</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_IncomeTaxReconciliationOtherPermanentItemsNet_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Other permanent items, net</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_IncomeTaxReconciliationOtherPermanentItemsNet_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Income Tax Reconciliation Other Permanent Items Net</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IncomeTaxReconciliationMinorityInterestIncomeExpense" xlink:type="locator" xlink:label="us-gaap_IncomeTaxReconciliationMinorityInterestIncomeExpense" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_IncomeTaxReconciliationMinorityInterestIncomeExpense_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Noncontrolling interests</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_IncomeTaxReconciliationMinorityInterestIncomeExpense_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Income Tax Reconciliation Minority Interest Income Expense</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IncomeTaxReconciliationOtherReconcilingItems" xlink:type="locator" xlink:label="us-gaap_IncomeTaxReconciliationOtherReconcilingItems" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_IncomeTaxReconciliationOtherReconcilingItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Other, net</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_IncomeTaxReconciliationOtherReconcilingItems" xlink:to="us-gaap_IncomeTaxReconciliationOtherReconcilingItems_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_IncomeTaxReconciliationOtherReconcilingItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Income Tax Reconciliation Other Reconciling Items</link:label>
    <link:label xml:lang="en-US" xlink:label="us-gaap_EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Tax at federal statutory tax rate</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationNondeductibleExpense" xlink:type="locator" xlink:label="us-gaap_EffectiveIncomeTaxRateReconciliationNondeductibleExpense" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_EffectiveIncomeTaxRateReconciliationNondeductibleExpense_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">S- corporation exclusion</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_EffectiveIncomeTaxRateReconciliationNondeductibleExpense_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Effective Income Tax Rate Reconciliation Nondeductible Expense</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes" xlink:type="locator" xlink:label="us-gaap_EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">State taxes, net of federal tax benefit</link:label>
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    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationChangeInEnactedTaxRate" xlink:type="locator" xlink:label="us-gaap_EffectiveIncomeTaxRateReconciliationChangeInEnactedTaxRate" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_EffectiveIncomeTaxRateReconciliationChangeInEnactedTaxRate_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Change in tax status</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_EffectiveIncomeTaxRateReconciliationChangeInEnactedTaxRate_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Effective Income Tax Rate Reconciliation Change In Enacted Tax Rate</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationChangeInDeferredTaxAssetsValuationAllowance" xlink:type="locator" xlink:label="us-gaap_EffectiveIncomeTaxRateReconciliationChangeInDeferredTaxAssetsValuationAllowance" />
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    <link:label xml:lang="en-US" xlink:label="us-gaap_EffectiveIncomeTaxRateReconciliationTaxContingencies_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Change in uncertain tax positions</link:label>
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    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationOtherReconcilingItemsPercent" xlink:type="locator" xlink:label="us-gaap_EffectiveIncomeTaxRateReconciliationOtherReconcilingItemsPercent" />
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    <link:loc xlink:href="psn-20191231.xsd#psn_ValuationAllowanceForeignTaxCredit" xlink:type="locator" xlink:label="psn_ValuationAllowanceForeignTaxCredit" />
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    <link:loc xlink:href="psn-20191231.xsd#psn_AccountsReceivableBilledCurrent" xlink:type="locator" xlink:label="psn_AccountsReceivableBilledCurrent" />
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    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefits" xlink:type="locator" xlink:label="us-gaap_DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefits" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefits_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Employee compensation and benefits</link:label>
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    <link:label xml:lang="en-US" xlink:label="psn_DeferredTaxAssetsRevenueAndCostRecognition_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Revenue and cost recognition</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_DeferredTaxAssetsRevenueAndCostRecognition_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Deferred Tax Assets Revenue And Cost Recognition</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsSelfInsurance" xlink:type="locator" xlink:label="us-gaap_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsSelfInsurance" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsSelfInsurance_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Insurance accruals</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsSelfInsurance_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Deferred Tax Assets Tax Deferred Expense Reserves And Accruals Self Insurance</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DeferredTaxAssetsOperatingLossCarryforwards" xlink:type="locator" xlink:label="us-gaap_DeferredTaxAssetsOperatingLossCarryforwards" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DeferredTaxAssetsOperatingLossCarryforwards_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Net operating losses</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_DeferredTaxAssetsOperatingLossCarryforwards_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Deferred Tax Assets Operating Loss Carryforwards</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_DeferredTaxAssetsLeaseLiability_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Lease liabilities</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_DeferredTaxAssetsLeaseLiability_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Deferred Tax Assets Lease Liability</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DeferredTaxAssetsTaxCreditCarryforwards" xlink:type="locator" xlink:label="us-gaap_DeferredTaxAssetsTaxCreditCarryforwards" />
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    <link:label xml:lang="en-US" xlink:label="us-gaap_DeferredTaxAssetsTaxCreditCarryforwards_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Deferred Tax Assets Tax Credit Carryforwards</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DeferredTaxAssetsOther" xlink:type="locator" xlink:label="us-gaap_DeferredTaxAssetsOther" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DeferredTaxAssetsOther_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Other</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_DeferredTaxAssetsOther_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Deferred Tax Assets Other</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DeferredTaxAssetsValuationAllowance" xlink:type="locator" xlink:label="us-gaap_DeferredTaxAssetsValuationAllowance" />
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    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DeferredTaxAssetsGross" xlink:type="locator" xlink:label="us-gaap_DeferredTaxAssetsGross" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DeferredTaxAssetsGross_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Total deferred tax assets</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_DeferredTaxAssetsGross_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Deferred Tax Assets Gross</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_DeferredTaxLiabilitiesAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Deferred tax liabilities</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_DeferredTaxLiabilitiesAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Deferred Tax Liabilities [Abstract]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DeferredTaxLiabilitiesGoodwillAndIntangibleAssetsIntangibleAssets" xlink:type="locator" xlink:label="us-gaap_DeferredTaxLiabilitiesGoodwillAndIntangibleAssetsIntangibleAssets" />
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    <link:label xml:lang="en-US" xlink:label="us-gaap_DeferredTaxLiabilitiesOther_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Other</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_DeferredTaxLiabilitiesOther_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Deferred Tax Liabilities Other</link:label>
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    <link:loc xlink:href="psn-20191231.xsd#psn_DeferredTaxOperatingLossCarryforwardsExpirationDescription" xlink:type="locator" xlink:label="psn_DeferredTaxOperatingLossCarryforwardsExpirationDescription" />
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    <link:loc xlink:href="psn-20191231.xsd#psn_DeferredTaxOperatingLossCarryforwardsExpirationYear" xlink:type="locator" xlink:label="psn_DeferredTaxOperatingLossCarryforwardsExpirationYear" />
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    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DeferredTaxAssetsOperatingLossCarryforwardsNotSubjectToExpiration" xlink:type="locator" xlink:label="us-gaap_DeferredTaxAssetsOperatingLossCarryforwardsNotSubjectToExpiration" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DeferredTaxAssetsOperatingLossCarryforwardsNotSubjectToExpiration_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Net operating loss carryforwards, not subject to expiration</link:label>
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    <link:loc xlink:href="psn-20191231.xsd#psn_TaxCreditCarryForwardExpirationYear" xlink:type="locator" xlink:label="psn_TaxCreditCarryForwardExpirationYear" />
    <link:label xml:lang="en-US" xlink:label="psn_TaxCreditCarryForwardExpirationYear_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Tax credit carry forward expiration year.</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_TaxCreditCarryforwardAmount_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Foreign tax credit carryforwards</link:label>
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    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_TaxCreditCarryforwardValuationAllowance" xlink:type="locator" xlink:label="us-gaap_TaxCreditCarryforwardValuationAllowance" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_TaxCreditCarryforwardValuationAllowance_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Foreign tax credits, valuation allowance</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_TaxCreditCarryforwardValuationAllowance_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Tax Credit Carryforward Valuation Allowance</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_TaxCreditCarryForwardExpirationYear_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Foreign tax credits, expiration year</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_TaxCreditCarryForwardExpirationYear_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Tax Credit Carry Forward Expiration Year</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IncomeTaxUncertaintiesAbstract" xlink:type="locator" xlink:label="us-gaap_IncomeTaxUncertaintiesAbstract" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_IncomeTaxUncertaintiesAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Income Tax Uncertainties [Abstract]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_IncomeTaxUncertaintiesAbstract" xlink:to="us-gaap_IncomeTaxUncertaintiesAbstract_lbl" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_UnrecognizedTaxBenefits" xlink:type="locator" xlink:label="us-gaap_UnrecognizedTaxBenefits" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_UnrecognizedTaxBenefits_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/periodStartLabel">Beginning of year</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_UnrecognizedTaxBenefits" xlink:to="us-gaap_UnrecognizedTaxBenefits_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_UnrecognizedTaxBenefits_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Unrecognized Tax Benefits</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromCurrentPeriodTaxPositions_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Increases&#8212;current year tax positions</link:label>
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    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromPriorPeriodTaxPositions" xlink:type="locator" xlink:label="us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromPriorPeriodTaxPositions" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromPriorPeriodTaxPositions_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel">Increases&#8212;prior year tax positions</link:label>
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    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_UnrecognizedTaxBenefitsDecreasesResultingFromSettlementsWithTaxingAuthorities" xlink:type="locator" xlink:label="us-gaap_UnrecognizedTaxBenefitsDecreasesResultingFromSettlementsWithTaxingAuthorities" />
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    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_UnrecognizedTaxBenefitsReductionsResultingFromLapseOfApplicableStatuteOfLimitations" xlink:type="locator" xlink:label="us-gaap_UnrecognizedTaxBenefitsReductionsResultingFromLapseOfApplicableStatuteOfLimitations" />
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    <link:label xml:lang="en-US" xlink:label="us-gaap_UnrecognizedTaxBenefits_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/periodEndLabel">End of year</link:label>
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    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestExpense" xlink:type="locator" xlink:label="us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestExpense" />
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    <link:label xml:lang="en-US" xlink:label="us-gaap_OpenTaxYear_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Open tax year</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_OpenTaxYear_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Open Tax Year</link:label>
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    <link:label xml:lang="en-US" xlink:label="psn_LossContingencyNumberOfClaims_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Loss contingency, number of claims.</link:label>
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    <link:label xml:lang="en-US" xlink:label="psn_LegalProceedingsTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Legal Proceedings [Table]</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_LegalProceedingsLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Legal Proceedings [Line Items]</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_LegalProceedingsLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Legal Proceedings [Line Items]</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_LossContingencyNumberOfClaims_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Number of claims outstanding</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_LossContingencyNumberOfClaims_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Loss Contingency Number Of Claims</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LossContingencyDamagesSoughtValue" xlink:type="locator" xlink:label="us-gaap_LossContingencyDamagesSoughtValue" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LossContingencyDamagesSoughtValue_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Loss contingency damages value</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LossContingencyDamagesSoughtValue" xlink:to="us-gaap_LossContingencyDamagesSoughtValue_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_LossContingencyDamagesSoughtValue_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Loss Contingency Damages Sought Value</link:label>
    <link:loc xlink:href="psn-20191231.xsd#psn_CommonStockSharesOutstandingIncludingEmployeeStockOwnershipPlanShares" xlink:type="locator" xlink:label="psn_CommonStockSharesOutstandingIncludingEmployeeStockOwnershipPlanShares" />
    <link:label xml:lang="en-US" xlink:label="psn_CommonStockSharesOutstandingIncludingEmployeeStockOwnershipPlanShares_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Common stock shares outstanding including employee stock ownership plan shares.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="psn_CommonStockSharesOutstandingIncludingEmployeeStockOwnershipPlanShares" xlink:to="psn_CommonStockSharesOutstandingIncludingEmployeeStockOwnershipPlanShares_lbl" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ScheduleOfEmployeeStockOwnershipPlanESOPDisclosuresTable" xlink:type="locator" xlink:label="us-gaap_ScheduleOfEmployeeStockOwnershipPlanESOPDisclosuresTable" />
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    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ScheduleOfEmployeeStockOwnershipPlanESOPDisclosuresTable" xlink:to="us-gaap_ScheduleOfEmployeeStockOwnershipPlanESOPDisclosuresTable_lbl" />
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    <link:loc xlink:href="psn-20191231.xsd#psn_DirectCostsOfContractsAndIndirectGeneralAndAdministrativeExpenseMember" xlink:type="locator" xlink:label="psn_DirectCostsOfContractsAndIndirectGeneralAndAdministrativeExpenseMember" />
    <link:label xml:lang="en-US" xlink:label="psn_DirectCostsOfContractsAndIndirectGeneralAndAdministrativeExpenseMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Direct costs of contracts and indirect, general and administrative expense.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="psn_DirectCostsOfContractsAndIndirectGeneralAndAdministrativeExpenseMember" xlink:to="psn_DirectCostsOfContractsAndIndirectGeneralAndAdministrativeExpenseMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="psn_DirectCostsOfContractsAndIndirectGeneralAndAdministrativeExpenseMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Direct Costs of Contracts and Indirect, General and Administrative Expense</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_DirectCostsOfContractsAndIndirectGeneralAndAdministrativeExpenseMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Direct Costs Of Contracts And Indirect General And Administrative Expense [Member]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OtherNoncurrentAssetsMember" xlink:type="locator" xlink:label="us-gaap_OtherNoncurrentAssetsMember" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_OtherNoncurrentAssetsMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Other Noncurrent Assets</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OtherNoncurrentAssetsMember" xlink:to="us-gaap_OtherNoncurrentAssetsMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_OtherNoncurrentAssetsMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Other Noncurrent Assets [Member]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_EmployeeStockOwnershipPlanESOPDisclosuresLineItems" xlink:type="locator" xlink:label="us-gaap_EmployeeStockOwnershipPlanESOPDisclosuresLineItems" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_EmployeeStockOwnershipPlanESOPDisclosuresLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Employee Stock Ownership Plan (ESOP) Disclosures [Line Items]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_EmployeeStockOwnershipPlanESOPDisclosuresLineItems" xlink:to="us-gaap_EmployeeStockOwnershipPlanESOPDisclosuresLineItems_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_EmployeeStockOwnershipPlanESOPDisclosuresLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Employee Stock Ownership Plan E S O P Disclosures [Line Items]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardDescription" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardDescription" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardDescription_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Shares fully vested, Description</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardDescription" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardDescription_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardDescription_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Share Based Compensation Arrangement By Share Based Payment Award Description</link:label>
    <link:label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel">Shares fully vested after credited service</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_CommonStockSharesOutstandingIncludingEmployeeStockOwnershipPlanShares_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Common stock shares outstanding including ESOP</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_CommonStockSharesOutstandingIncludingEmployeeStockOwnershipPlanShares_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Common Stock Shares Outstanding Including Employee Stock Ownership Plan Shares</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_EmployeeStockOwnershipPlanESOPSharesInESOP" xlink:type="locator" xlink:label="us-gaap_EmployeeStockOwnershipPlanESOPSharesInESOP" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_EmployeeStockOwnershipPlanESOPSharesInESOP_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel">Company&apos;s stock held by ESOP</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_EmployeeStockOwnershipPlanESOPSharesInESOP" xlink:to="us-gaap_EmployeeStockOwnershipPlanESOPSharesInESOP_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_EmployeeStockOwnershipPlanESOPSharesInESOP_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Employee Stock Ownership Plan E S O P Shares In E S O P</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_TemporaryEquityValueExcludingAdditionalPaidInCapital" xlink:type="locator" xlink:label="us-gaap_TemporaryEquityValueExcludingAdditionalPaidInCapital" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_TemporaryEquityValueExcludingAdditionalPaidInCapital_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">ESOP shares redemption, value</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_TemporaryEquityValueExcludingAdditionalPaidInCapital" xlink:to="us-gaap_TemporaryEquityValueExcludingAdditionalPaidInCapital_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_TemporaryEquityValueExcludingAdditionalPaidInCapital_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Temporary Equity Value Excluding Additional Paid In Capital</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_EmployeeStockOwnershipPlanESOPCompensationExpense" xlink:type="locator" xlink:label="us-gaap_EmployeeStockOwnershipPlanESOPCompensationExpense" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_EmployeeStockOwnershipPlanESOPCompensationExpense_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">ESOP contribution expense</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_EmployeeStockOwnershipPlanESOPCompensationExpense" xlink:to="us-gaap_EmployeeStockOwnershipPlanESOPCompensationExpense_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_EmployeeStockOwnershipPlanESOPCompensationExpense_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Employee Stock Ownership Plan E S O P Compensation Expense</link:label>
    <link:loc xlink:href="psn-20191231.xsd#psn_EmployeeStockOwnershipPlanESOPDividendsDeclaredPerShare" xlink:type="locator" xlink:label="psn_EmployeeStockOwnershipPlanESOPDividendsDeclaredPerShare" />
    <link:label xml:lang="en-US" xlink:label="psn_EmployeeStockOwnershipPlanESOPDividendsDeclaredPerShare_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Employee stock ownership plan ESOP dividends declared per share.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="psn_EmployeeStockOwnershipPlanESOPDividendsDeclaredPerShare" xlink:to="psn_EmployeeStockOwnershipPlanESOPDividendsDeclaredPerShare_lbl" />
    <link:loc xlink:href="psn-20191231.xsd#psn_EmployeeStockOwnershipPlanESOPDividendsDeclaredToESOP" xlink:type="locator" xlink:label="psn_EmployeeStockOwnershipPlanESOPDividendsDeclaredToESOP" />
    <link:label xml:lang="en-US" xlink:label="psn_EmployeeStockOwnershipPlanESOPDividendsDeclaredToESOP_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Employee stock ownership plan ESOP dividends declared to ESOP.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="psn_EmployeeStockOwnershipPlanESOPDividendsDeclaredToESOP" xlink:to="psn_EmployeeStockOwnershipPlanESOPDividendsDeclaredToESOP_lbl" />
    <link:loc xlink:href="psn-20191231.xsd#psn_EmployeeStockOwnershipPlanESOPDividendsPaymentDate" xlink:type="locator" xlink:label="psn_EmployeeStockOwnershipPlanESOPDividendsPaymentDate" />
    <link:label xml:lang="en-US" xlink:label="psn_EmployeeStockOwnershipPlanESOPDividendsPaymentDate_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Employee stock ownership plan ESOP dividends payment date.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="psn_EmployeeStockOwnershipPlanESOPDividendsPaymentDate" xlink:to="psn_EmployeeStockOwnershipPlanESOPDividendsPaymentDate_lbl" />
    <link:loc xlink:href="psn-20191231.xsd#psn_EmployeeStockOwnershipPlanESOPDividendsDeclaredDate" xlink:type="locator" xlink:label="psn_EmployeeStockOwnershipPlanESOPDividendsDeclaredDate" />
    <link:label xml:lang="en-US" xlink:label="psn_EmployeeStockOwnershipPlanESOPDividendsDeclaredDate_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Employee stock ownership plan ESOP dividends declared date.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="psn_EmployeeStockOwnershipPlanESOPDividendsDeclaredDate" xlink:to="psn_EmployeeStockOwnershipPlanESOPDividendsDeclaredDate_lbl" />
    <link:label xml:lang="en-US" xlink:label="psn_EmployeeStockOwnershipPlanESOPDividendsDeclaredDate_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">ESOP dividends declared date</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_EmployeeStockOwnershipPlanESOPDividendsDeclaredDate_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Employee Stock Ownership Plan E S O P Dividends Declared Date</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_EmployeeStockOwnershipPlanESOPDividendsDeclaredPerShare_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">ESOP dividends declared per share</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_EmployeeStockOwnershipPlanESOPDividendsDeclaredPerShare_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Employee Stock Ownership Plan E S O P Dividends Declared Per Share</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_EmployeeStockOwnershipPlanESOPDividendsDeclaredToESOP_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">ESOP dividends declared amount</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_EmployeeStockOwnershipPlanESOPDividendsDeclaredToESOP_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Employee Stock Ownership Plan E S O P Dividends Declared To E S O P</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_EmployeeStockOwnershipPlanESOPDividendsPaymentDate_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">ESOP dividends payment date</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_EmployeeStockOwnershipPlanESOPDividendsPaymentDate_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Employee Stock Ownership Plan E S O P Dividends Payment Date</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DividendsCommonStock" xlink:type="locator" xlink:label="us-gaap_DividendsCommonStock" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DividendsCommonStock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Dividends declared amount</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DividendsCommonStock" xlink:to="us-gaap_DividendsCommonStock_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DividendsCommonStock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Dividends Common Stock</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DefinedContributionPlanEmployerDiscretionaryContributionAmount" xlink:type="locator" xlink:label="us-gaap_DefinedContributionPlanEmployerDiscretionaryContributionAmount" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DefinedContributionPlanEmployerDiscretionaryContributionAmount_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Contribution to 401 (k) plan</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DefinedContributionPlanEmployerDiscretionaryContributionAmount" xlink:to="us-gaap_DefinedContributionPlanEmployerDiscretionaryContributionAmount_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DefinedContributionPlanEmployerDiscretionaryContributionAmount_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Defined Contribution Plan Employer Discretionary Contribution Amount</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DefinedBenefitPlanAssetsForPlanBenefitsNoncurrent" xlink:type="locator" xlink:label="us-gaap_DefinedBenefitPlanAssetsForPlanBenefitsNoncurrent" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DefinedBenefitPlanAssetsForPlanBenefitsNoncurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Defined benefit pension plan, net assets position</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DefinedBenefitPlanAssetsForPlanBenefitsNoncurrent" xlink:to="us-gaap_DefinedBenefitPlanAssetsForPlanBenefitsNoncurrent_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_DefinedBenefitPlanAssetsForPlanBenefitsNoncurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Defined Benefit Plan Assets For Plan Benefits Noncurrent</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ScheduleOfEquityMethodInvestmentsTable" xlink:type="locator" xlink:label="us-gaap_ScheduleOfEquityMethodInvestmentsTable" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ScheduleOfEquityMethodInvestmentsTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Schedule Of Equity Method Investments [Table]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ScheduleOfEquityMethodInvestmentsTable" xlink:to="us-gaap_ScheduleOfEquityMethodInvestmentsTable_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_ScheduleOfEquityMethodInvestmentsTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Schedule Of Equity Method Investments [Table]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis" xlink:type="locator" xlink:label="srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis" />
    <link:label xml:lang="en-US" xlink:label="srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Investment, Name</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis" xlink:to="srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_lbl" />
    <link:label xml:lang="en-US" xlink:label="srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Schedule Of Equity Method Investment Equity Method Investee Name [Axis]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_EquityMethodInvesteeNameDomain" xlink:type="locator" xlink:label="srt_EquityMethodInvesteeNameDomain" />
    <link:label xml:lang="en-US" xlink:label="srt_EquityMethodInvesteeNameDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Investment, Name</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="srt_EquityMethodInvesteeNameDomain" xlink:to="srt_EquityMethodInvesteeNameDomain_lbl" />
    <link:label xml:lang="en-US" xlink:label="srt_EquityMethodInvesteeNameDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Equity Method Investee Name [Domain]</link:label>
    <link:loc xlink:href="psn-20191231.xsd#psn_UnconsolidatedJointVenturesMember" xlink:type="locator" xlink:label="psn_UnconsolidatedJointVenturesMember" />
    <link:label xml:lang="en-US" xlink:label="psn_UnconsolidatedJointVenturesMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Unconsolidated joint ventures.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="psn_UnconsolidatedJointVenturesMember" xlink:to="psn_UnconsolidatedJointVenturesMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="psn_UnconsolidatedJointVenturesMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Unconsolidated Joint Ventures</link:label>
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    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ScheduleOfEquityMethodInvestmentsLineItems" xlink:type="locator" xlink:label="us-gaap_ScheduleOfEquityMethodInvestmentsLineItems" />
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    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LiabilitiesNoncurrent" xlink:to="us-gaap_LiabilitiesNoncurrent_lbl" />
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    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_MajorityOwnedSubsidiaryUnconsolidatedMember" xlink:type="locator" xlink:label="us-gaap_MajorityOwnedSubsidiaryUnconsolidatedMember" />
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    <link:label xml:lang="en-US" xlink:label="us-gaap_RelatedPartyTransactionLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Related Party Transaction [Line Items]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_RelatedPartyTransactionOtherRevenuesFromTransactionsWithRelatedParty" xlink:type="locator" xlink:label="us-gaap_RelatedPartyTransactionOtherRevenuesFromTransactionsWithRelatedParty" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_RelatedPartyTransactionOtherRevenuesFromTransactionsWithRelatedParty_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Revenues</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_RelatedPartyTransactionOtherRevenuesFromTransactionsWithRelatedParty_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Related Party Transaction Other Revenues From Transactions With Related Party</link:label>
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    <link:label xml:lang="en-US" xlink:label="psn_ReimbursableCostIncurred_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Reimbursable Cost Incurred</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AccountsReceivableRelatedPartiesCurrent" xlink:type="locator" xlink:label="us-gaap_AccountsReceivableRelatedPartiesCurrent" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_AccountsReceivableRelatedPartiesCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Accounts receivable</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_AccountsReceivableRelatedPartiesCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Accounts Receivable Related Parties Current</link:label>
    <link:label xml:lang="en-US" xlink:label="us-gaap_ContractWithCustomerLiabilityCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Contract liabilities</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_FairValueMeasurementsFairValueHierarchyDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Fair Value Measurements Fair Value Hierarchy [Domain]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FairValueInputsLevel1Member" xlink:type="locator" xlink:label="us-gaap_FairValueInputsLevel1Member" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_FairValueInputsLevel1Member_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Level 1</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_FairValueInputsLevel1Member_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Fair Value Inputs Level1 [Member]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FairValueInputsLevel2Member" xlink:type="locator" xlink:label="us-gaap_FairValueInputsLevel2Member" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_FairValueInputsLevel2Member_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Level 2</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_FairValueInputsLevel2Member_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Fair Value Inputs Level2 [Member]</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_FairValueInputsLevel3Member_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Level 3</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_FairValueInputsLevel3Member_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Fair Value Inputs Level3 [Member]</link:label>
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    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems" xlink:type="locator" xlink:label="us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems" />
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    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems" xlink:to="us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_lbl" />
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    <link:loc xlink:href="psn-20191231.xsd#psn_RedeemableEquityCommonStockCarryingAmount" xlink:type="locator" xlink:label="psn_RedeemableEquityCommonStockCarryingAmount" />
    <link:label xml:lang="en-US" xlink:label="psn_RedeemableEquityCommonStockCarryingAmount_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Redeemable equity common stock carrying amount.</link:label>
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    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_EmployeeStockOwnershipPlanESOPNumberOfAllocatedShares" xlink:type="locator" xlink:label="us-gaap_EmployeeStockOwnershipPlanESOPNumberOfAllocatedShares" />
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    <link:loc xlink:href="psn-20191231.xsd#psn_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityPurchasesOfTreasuryStock" xlink:type="locator" xlink:label="psn_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityPurchasesOfTreasuryStock" />
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    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="psn_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityPurchasesOfTreasuryStock" xlink:to="psn_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityPurchasesOfTreasuryStock_lbl" />
    <link:loc xlink:href="psn-20191231.xsd#psn_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityContributionsOfTreasuryStockToESOP" xlink:type="locator" xlink:label="psn_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityContributionsOfTreasuryStockToESOP" />
    <link:label xml:lang="en-US" xlink:label="psn_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityContributionsOfTreasuryStockToESOP_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Fair value measurement with unobservable inputs reconciliation recurring basis liability contributions of treasury stock to ESOP</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="psn_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityContributionsOfTreasuryStockToESOP" xlink:to="psn_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityContributionsOfTreasuryStockToESOP_lbl" />
    <link:loc xlink:href="psn-20191231.xsd#psn_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilitySharePriceAdjustment" xlink:type="locator" xlink:label="psn_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilitySharePriceAdjustment" />
    <link:label xml:lang="en-US" xlink:label="psn_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilitySharePriceAdjustment_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Fair value measurement with unobservable inputs reconciliation recurring basis liability share price adjustment.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="psn_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilitySharePriceAdjustment" xlink:to="psn_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilitySharePriceAdjustment_lbl" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityTransfersNetAbstract" xlink:type="locator" xlink:label="us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityTransfersNetAbstract" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityTransfersNetAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Liability Transfers Net [Abstract]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityTransfersNetAbstract" xlink:to="us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityTransfersNetAbstract_lbl" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue" xlink:type="locator" xlink:label="us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/periodStartLabel">Balance at beginning of year</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue" xlink:to="us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Fair Value Measurement With Unobservable Inputs Reconciliations Recurring Basis Liability Value</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityPurchasesOfTreasuryStock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Purchases of treasury stock</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityPurchasesOfTreasuryStock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Liability Purchases Of Treasury Stock</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityContributionsOfTreasuryStockToESOP_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Contributions of treasury stock to ESOP</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityContributionsOfTreasuryStockToESOP_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Liability Contributions Of Treasury Stock To E S O P</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilitySharePriceAdjustment_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Share price adjustment</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilitySharePriceAdjustment_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Liability Share Price Adjustment</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationLiabilityTransfersOutOfLevel3" xlink:type="locator" xlink:label="us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationLiabilityTransfersOutOfLevel3" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationLiabilityTransfersOutOfLevel3_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Transfer to permanent equity</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationLiabilityTransfersOutOfLevel3_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Fair Value Measurement With Unobservable Inputs Reconciliation Liability Transfers Out Of Level3</link:label>
    <link:label xml:lang="en-US" xlink:label="us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/periodEndLabel">Balance at end of year</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount" xlink:type="locator" xlink:label="us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Dilutive securities outstanding</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingBasic" xlink:type="locator" xlink:label="us-gaap_WeightedAverageNumberOfSharesOutstandingBasic" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Basic weighted average number of shares outstanding</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_WeightedAverageNumberOfSharesOutstandingBasic" xlink:to="us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Weighted Average Number Of Shares Outstanding Basic</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_WeightedAverageNumberDilutedSharesOutstandingAdjustment" xlink:type="locator" xlink:label="us-gaap_WeightedAverageNumberDilutedSharesOutstandingAdjustment" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_WeightedAverageNumberDilutedSharesOutstandingAdjustment_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Dilutive common share equivalents</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_WeightedAverageNumberDilutedSharesOutstandingAdjustment_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Weighted Average Number Diluted Shares Outstanding Adjustment</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding" xlink:type="locator" xlink:label="us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Diluted weighted average number of shares outstanding</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding" xlink:to="us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Weighted Average Number Of Diluted Shares Outstanding</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable" xlink:type="locator" xlink:label="us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable" />
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    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_StatementGeographicalAxis" xlink:type="locator" xlink:label="srt_StatementGeographicalAxis" />
    <link:label xml:lang="en-US" xlink:label="srt_StatementGeographicalAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Geographical</link:label>
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    <link:label xml:lang="en-US" xlink:label="srt_SegmentGeographicalDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Geographical</link:label>
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    <link:label xml:lang="en-US" xlink:label="country_US_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">United States</link:label>
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    <link:label xml:lang="en-US" xlink:label="country_US_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">UNITED STATES</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_SalesMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Sales [Member]</link:label>
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    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SubsegmentsAxis" xlink:to="us-gaap_SubsegmentsAxis_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_SubsegmentsAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Subsegments [Axis]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_SubsegmentsDomain" xlink:type="locator" xlink:label="us-gaap_SubsegmentsDomain" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_SubsegmentsDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Subsegments</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SubsegmentsDomain" xlink:to="us-gaap_SubsegmentsDomain_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_SubsegmentsDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Subsegments [Domain]</link:label>
    <link:loc xlink:href="psn-20191231.xsd#psn_MobilitySolutionsMember" xlink:type="locator" xlink:label="psn_MobilitySolutionsMember" />
    <link:label xml:lang="en-US" xlink:label="psn_MobilitySolutionsMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Mobility solutions.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="psn_MobilitySolutionsMember" xlink:to="psn_MobilitySolutionsMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="psn_MobilitySolutionsMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Mobility Solutions</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_MobilitySolutionsMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Mobility Solutions [Member]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_SegmentReportingInformationLineItems" xlink:type="locator" xlink:label="us-gaap_SegmentReportingInformationLineItems" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_SegmentReportingInformationLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Segment Reporting Information [Line Items]</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SegmentReportingInformationLineItems" xlink:to="us-gaap_SegmentReportingInformationLineItems_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_SegmentReportingInformationLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Segment Reporting Information [Line Items]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_NumberOfReportableSegments" xlink:type="locator" xlink:label="us-gaap_NumberOfReportableSegments" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_NumberOfReportableSegments_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Number of reportable segments</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_NumberOfReportableSegments" xlink:to="us-gaap_NumberOfReportableSegments_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_NumberOfReportableSegments_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Number Of Reportable Segments</link:label>
    <link:label xml:lang="en-US" xlink:label="us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/positiveLabel">Total revenues</link:label>
    <link:loc xlink:href="psn-20191231.xsd#psn_ReconciliationFromNetIncomeToAdjustedEBITDAAbstract" xlink:type="locator" xlink:label="psn_ReconciliationFromNetIncomeToAdjustedEBITDAAbstract" />
    <link:label xml:lang="en-US" xlink:label="psn_ReconciliationFromNetIncomeToAdjustedEBITDAAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Reconciliation from net income to adjusted EBITDA.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="psn_ReconciliationFromNetIncomeToAdjustedEBITDAAbstract" xlink:to="psn_ReconciliationFromNetIncomeToAdjustedEBITDAAbstract_lbl" />
    <link:label xml:lang="en-US" xlink:label="psn_ReconciliationFromNetIncomeToAdjustedEBITDAAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Adjusted EBITDA attributable to Parsons Corporation</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_ReconciliationFromNetIncomeToAdjustedEBITDAAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Reconciliation From Net Income To Adjusted E B I T D A [Abstract]</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_AdjustedEBITDAAttributableToParent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Adjusted EBITDA attributable to Parsons Corporation</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_AdjustedEBITDAAttributableToParent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Adjusted E B I T D A Attributable To Parent</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_AdjustedEBITDAAttributableToNoncontrollingInterests_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Adjusted EBITDA attributable to noncontrolling interests</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_AdjustedEBITDAAttributableToNoncontrollingInterests_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Adjusted E B I T D A Attributable To Noncontrolling Interests</link:label>
    <link:label xml:lang="en-US" xlink:label="us-gaap_DepreciationAndAmortization_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Depreciation and amortization</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_InterestIncomeExpenseNet" xlink:type="locator" xlink:label="us-gaap_InterestIncomeExpenseNet" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_InterestIncomeExpenseNet_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Interest expense, net</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_InterestIncomeExpenseNet" xlink:to="us-gaap_InterestIncomeExpenseNet_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_InterestIncomeExpenseNet_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Interest Income Expense Net</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_LitigationClaimSettlementRelatedExpenseIncome_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Litigation-related expenses</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_LitigationClaimSettlementRelatedExpenseIncome_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Litigation Claim Settlement Related Expense Income</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_SaleLeasebackTransactionAmortizationOfDeferredGain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel">Amortization of deferred gain resulting from sale- leaseback transactions</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AllocatedShareBasedCompensationExpense" xlink:type="locator" xlink:label="us-gaap_AllocatedShareBasedCompensationExpense" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_AllocatedShareBasedCompensationExpense_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Equity-based compensation</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AllocatedShareBasedCompensationExpense" xlink:to="us-gaap_AllocatedShareBasedCompensationExpense_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_AllocatedShareBasedCompensationExpense_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Allocated Share Based Compensation Expense</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_TransactionRelatedCosts_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Transaction-related costs</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_TransactionRelatedCosts_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Transaction Related Costs</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_RestructuringCharges" xlink:type="locator" xlink:label="us-gaap_RestructuringCharges" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_RestructuringCharges_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Restructuring</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_RestructuringCharges" xlink:to="us-gaap_RestructuringCharges_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_RestructuringCharges_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Restructuring Charges</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_OtherReconciliationFromNetIncomeToAdjustedEBITDA_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Other</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_OtherReconciliationFromNetIncomeToAdjustedEBITDA_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Other Reconciliation From Net Income To Adjusted E B I T D A</link:label>
    <link:label xml:lang="en-US" xlink:label="us-gaap_ProfitLoss_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Net income including noncontrolling interests</link:label>
    <link:loc xlink:href="psn-20191231.xsd#psn_OtherNonoperatingIncomeMember" xlink:type="locator" xlink:label="psn_OtherNonoperatingIncomeMember" />
    <link:label xml:lang="en-US" xlink:label="psn_OtherNonoperatingIncomeMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Other nonoperating income.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="psn_OtherNonoperatingIncomeMember" xlink:to="psn_OtherNonoperatingIncomeMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="psn_OtherNonoperatingIncomeMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Other Income</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_OtherNonoperatingIncomeMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Other Nonoperating Income [Member]</link:label>
    <link:label xml:lang="en-US" xlink:label="us-gaap_GainLossRelatedToLitigationSettlement_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel">Reversal of accrued liability</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_NorthAmericaMember" xlink:type="locator" xlink:label="srt_NorthAmericaMember" />
    <link:label xml:lang="en-US" xlink:label="srt_NorthAmericaMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">North America</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="srt_NorthAmericaMember" xlink:to="srt_NorthAmericaMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="srt_NorthAmericaMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">North America [Member]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_MiddleEastMember" xlink:type="locator" xlink:label="us-gaap_MiddleEastMember" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_MiddleEastMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Middle East</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_MiddleEastMember" xlink:to="us-gaap_MiddleEastMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_MiddleEastMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Middle East [Member]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_NonUsMember" xlink:type="locator" xlink:label="us-gaap_NonUsMember" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_NonUsMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Rest of World</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_NonUsMember" xlink:to="us-gaap_NonUsMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_NonUsMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Non Us [Member]</link:label>
    <link:loc xlink:href="psn-20191231.xsd#psn_CyberAndIntelligenceMember" xlink:type="locator" xlink:label="psn_CyberAndIntelligenceMember" />
    <link:label xml:lang="en-US" xlink:label="psn_CyberAndIntelligenceMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Cyber &amp; Intelligence.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="psn_CyberAndIntelligenceMember" xlink:to="psn_CyberAndIntelligenceMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="psn_CyberAndIntelligenceMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Cyber &amp; Intelligence</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_CyberAndIntelligenceMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Cyber And Intelligence [Member]</link:label>
    <link:loc xlink:href="psn-20191231.xsd#psn_DefenseMember" xlink:type="locator" xlink:label="psn_DefenseMember" />
    <link:label xml:lang="en-US" xlink:label="psn_DefenseMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Defense.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="psn_DefenseMember" xlink:to="psn_DefenseMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="psn_DefenseMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Defense</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_DefenseMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Defense [Member]</link:label>
    <link:loc xlink:href="psn-20191231.xsd#psn_MissionSolutionsMember" xlink:type="locator" xlink:label="psn_MissionSolutionsMember" />
    <link:label xml:lang="en-US" xlink:label="psn_MissionSolutionsMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Mission solutions.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="psn_MissionSolutionsMember" xlink:to="psn_MissionSolutionsMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="psn_MissionSolutionsMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Mission Solutions</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_MissionSolutionsMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Mission Solutions [Member]</link:label>
    <link:loc xlink:href="psn-20191231.xsd#psn_EngineeredSystemsMember" xlink:type="locator" xlink:label="psn_EngineeredSystemsMember" />
    <link:label xml:lang="en-US" xlink:label="psn_EngineeredSystemsMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Engineered systems.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="psn_EngineeredSystemsMember" xlink:to="psn_EngineeredSystemsMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="psn_EngineeredSystemsMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Engineered Systems</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_EngineeredSystemsMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Engineered Systems [Member]</link:label>
    <link:loc xlink:href="psn-20191231.xsd#psn_GeospatialMember" xlink:type="locator" xlink:label="psn_GeospatialMember" />
    <link:label xml:lang="en-US" xlink:label="psn_GeospatialMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Geospatial.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="psn_GeospatialMember" xlink:to="psn_GeospatialMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="psn_GeospatialMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Geospatial</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_GeospatialMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Geospatial [Member]</link:label>
    <link:loc xlink:href="psn-20191231.xsd#psn_ConnectCommunitiesMember" xlink:type="locator" xlink:label="psn_ConnectCommunitiesMember" />
    <link:label xml:lang="en-US" xlink:label="psn_ConnectCommunitiesMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Connect communities.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="psn_ConnectCommunitiesMember" xlink:to="psn_ConnectCommunitiesMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="psn_ConnectCommunitiesMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Connect Communities</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_ConnectCommunitiesMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Connect Communities [Member]</link:label>
    <link:loc xlink:href="psn-20191231.xsd#psn_IndustrialMember" xlink:type="locator" xlink:label="psn_IndustrialMember" />
    <link:label xml:lang="en-US" xlink:label="psn_IndustrialMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Industrial.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="psn_IndustrialMember" xlink:to="psn_IndustrialMember_lbl" />
    <link:label xml:lang="en-US" xlink:label="psn_IndustrialMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Industrial</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_IndustrialMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Industrial [Member]</link:label>
    <link:loc xlink:href="psn-20191231.xsd#psn_RevenueExcludingClaimSettlement" xlink:type="locator" xlink:label="psn_RevenueExcludingClaimSettlement" />
    <link:label xml:lang="en-US" xlink:label="psn_RevenueExcludingClaimSettlement_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Revenue excluding claim settlement.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="psn_RevenueExcludingClaimSettlement" xlink:to="psn_RevenueExcludingClaimSettlement_lbl" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_GainLossRelatedToLitigationSettlement_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Litigation-related expenses</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_RevenueExcludingClaimSettlement_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Revenue Excluding Claim Settlement</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_RevenueExcludingClaimSettlement_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Revenue Excluding Claim Settlement</link:label>
    <link:loc xlink:href="psn-20191231.xsd#psn_QuarterlyFinancialInformationLineItems" xlink:type="locator" xlink:label="psn_QuarterlyFinancialInformationLineItems" />
    <link:label xml:lang="en-US" xlink:label="psn_QuarterlyFinancialInformationLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Quarterly financial information.</link:label>
    <link:labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="psn_QuarterlyFinancialInformationLineItems" xlink:to="psn_QuarterlyFinancialInformationLineItems_lbl" />
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    <link:label xml:lang="en-US" xlink:label="psn_QuarterlyFinancialInformationTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Quarterly Financial Information [Table]</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_QuarterlyFinancialInformationLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Quarterly Financial Information [Line Items]</link:label>
    <link:label xml:lang="en-US" xlink:label="psn_QuarterlyFinancialInformationLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Quarterly Financial Information [Line Items]</link:label>
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    <link:label xml:lang="en-US" xlink:label="us-gaap_ValuationAllowancesAndReservesDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">SEC Schedule, 12-09, Valuation Allowances and Reserves</link:label>
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    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AllowanceForCreditLossMember" xlink:type="locator" xlink:label="us-gaap_AllowanceForCreditLossMember" />
    <link:label xml:lang="en-US" xlink:label="us-gaap_AllowanceForCreditLossMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Allowance for Doubtful Accounts</link:label>
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