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  <xs:element id="htld_CommonStockDividendsDeclaredInAccountsPayable" abstract="false" name="CommonStockDividendsDeclaredInAccountsPayable" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="htld_IncreasetoCashfromInvestingActivityAbstract" abstract="true" name="IncreasetoCashfromInvestingActivityAbstract" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:stringItemType"/>
  <xs:element id="htld_BasisofPresentationandAccountingPronouncementsAbstract" abstract="true" name="BasisofPresentationandAccountingPronouncementsAbstract" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:stringItemType"/>
  <xs:element id="htld_UseofEstimatesAbstract" abstract="true" name="UseofEstimatesAbstract" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:stringItemType"/>
  <xs:element id="htld_PropertyPlantandDepreciationAbstract" abstract="true" name="PropertyPlantandDepreciationAbstract" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:stringItemType"/>
  <xs:element id="htld_ShareRepurchasesAbstract" abstract="true" name="ShareRepurchasesAbstract" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:stringItemType"/>
  <xs:element id="htld_BasisofPresentationAbstract" abstract="true" name="BasisofPresentationAbstract" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:stringItemType"/>
  <xs:element id="htld_SummaryOfPositionsForWhichSignificantChangeInUnrecognizedTaxBenefitsIsReasonablyPossibleTextBlockTextBlock" abstract="false" name="SummaryOfPositionsForWhichSignificantChangeInUnrecognizedTaxBenefitsIsReasonablyPossibleTextBlockTextBlock" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:textBlockItemType"/>
  <xs:element id="htld_FuelsurchargeMember" abstract="true" name="FuelsurchargeMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="htld_FuelSurchargeRevenue" abstract="false" name="FuelSurchargeRevenue" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="htld_RestrictedCashAndInvestmentsCurrentTotal" abstract="false" name="RestrictedCashAndInvestmentsCurrentTotal" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="htld_FinancialStatementLocationAxis" abstract="true" name="FinancialStatementLocationAxis" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrldt:dimensionItem" type="xbrli:stringItemType"/>
  <xs:element id="htld_FinancialStatementLocationDomain" abstract="true" name="FinancialStatementLocationDomain" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="htld_AmortizationPeriodOfTires" abstract="false" name="AmortizationPeriodOfTires" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:stringItemType"/>
  <xs:element id="htld_IncreaseDecreaseOfRestrictedCashAndInvestments" abstract="false" name="IncreaseDecreaseOfRestrictedCashAndInvestments" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="htld_NetIncomeLossEPS" abstract="false" name="NetIncomeLossEPS" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="htld_RestrictedStockSharesAuthorized" abstract="false" name="RestrictedStockSharesAuthorized" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:sharesItemType"/>
  <xs:element id="htld_RestrictedStockSharesRemainingAvailable" abstract="false" name="RestrictedStockSharesRemainingAvailable" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:sharesItemType"/>
  <xs:element id="htld_ABRLoanMember" abstract="true" name="ABRLoanMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="htld_AccordionFeatureAxis" abstract="true" name="AccordionFeatureAxis" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrldt:dimensionItem" type="xbrli:stringItemType"/>
  <xs:element id="htld_AccordionFeatureDomain" abstract="true" name="AccordionFeatureDomain" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="htld_BusinessCombinationLongTermDebt" abstract="false" name="BusinessCombinationLongTermDebt" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="htld_FinanceLeaseObligations" abstract="false" name="FinanceLeaseObligations" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="htld_Debt" abstract="false" name="Debt" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="htld_UnsecuredCreditFacility" abstract="false" name="UnsecuredCreditFacility" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="htld_RevolvingFacility" abstract="false" name="RevolvingFacility" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="htld_TermFacility" abstract="false" name="TermFacility" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="htld_SwinglineFacility" abstract="false" name="SwinglineFacility" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="htld_AvailableIssuanceOfLineOfCredit" abstract="false" name="AvailableIssuanceOfLineOfCredit" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="htld_UncommittedAccordionFeature" abstract="false" name="UncommittedAccordionFeature" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="htld_OutstandingDebtOnTermFacility" abstract="false" name="OutstandingDebtOnTermFacility" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="htld_OutstandingDebtOnRevolvingFacility" abstract="false" name="OutstandingDebtOnRevolvingFacility" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="htld_WeightedAverageInterestRateCreditFacility" abstract="false" name="WeightedAverageInterestRateCreditFacility" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="htld_DebtInstrumentCovenantDistributionsMaxLeverageRatio" abstract="false" name="DebtInstrumentCovenantDistributionsMaxLeverageRatio" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:pureItemType"/>
  <xs:element id="htld_DebtInstrumentCovenantMinimumInterestCoverageRatio" abstract="false" name="DebtInstrumentCovenantMinimumInterestCoverageRatio" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:pureItemType"/>
  <xs:element id="htld_DebtInstrumentCovenantMaximumNetLeverageRatio" abstract="false" name="DebtInstrumentCovenantMaximumNetLeverageRatio" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:pureItemType"/>
  <xs:element id="htld_MaxAnnualDividend" abstract="false" name="MaxAnnualDividend" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="htld_ApplicableMarginBase" abstract="false" name="ApplicableMarginBase" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:pureItemType"/>
  <xs:element id="htld_TermSOFROneMonthSpread" abstract="false" name="TermSOFROneMonthSpread" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:pureItemType"/>
  <xs:element id="htld_OperatingLeasesAbstract" abstract="true" name="OperatingLeasesAbstract" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:stringItemType"/>
  <xs:element id="htld_RightOfUseAssetAssociatedWithTheLeasedTerminalFacilities" abstract="false" name="RightOfUseAssetAssociatedWithTheLeasedTerminalFacilities" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="htld_RightOfUseOperatingLeaseAssets" abstract="false" name="RightOfUseOperatingLeaseAssets" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="htld_RepurchaseOfCommonStockShares" abstract="false" name="RepurchaseOfCommonStockShares" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:sharesItemType"/>
  <xs:element id="htld_PaymentsForRepurchaseOfCommonStock1" abstract="false" name="PaymentsForRepurchaseOfCommonStock1" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
</xs:schema>
