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      <filer>
        <filerCredentials>
          <cik>0001374429</cik>
          <ccc>XXXXXXXX</ccc>
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      </filer>
      <liveTestFlag>LIVE</liveTestFlag>



    </filerInfo>
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  <formData>
    <issuerInfo>
      <issuerCik>0000040211</issuerCik>
      <issuerName>GATX CORP</issuerName>
      <secFileNumber>001-02328</secFileNumber>
      <issuerAddress>
        <com:street1>233 SOUTH WACKER DRIVE</com:street1>
        <com:city>CHICAGO</com:city>
        <com:stateOrCountry>IL</com:stateOrCountry>
        <com:zipCode>60606-7147</com:zipCode>
      </issuerAddress>
      <issuerContactPhone>3126216200</issuerContactPhone>
      <nameOfPersonForWhoseAccountTheSecuritiesAreToBeSold>Arvia Anne L</nameOfPersonForWhoseAccountTheSecuritiesAreToBeSold>
      <relationshipsToIssuer>
        <relationshipToIssuer>Director</relationshipToIssuer>
      </relationshipsToIssuer>
    </issuerInfo>
    <securitiesInformation>
      <securitiesClassTitle>Common</securitiesClassTitle>
      <brokerOrMarketmakerDetails>
        <name>Charles Schwan Corporation</name>
        <address>
          <com:street1>3000 Schwab Way</com:street1>
          <com:city>Westlake</com:city>
          <com:stateOrCountry>TX</com:stateOrCountry>
          <com:zipCode>76262</com:zipCode>
        </address>
      </brokerOrMarketmakerDetails>
      <noOfUnitsSold>1000</noOfUnitsSold>
      <aggregateMarketValue>132450.00</aggregateMarketValue>
      <noOfUnitsOutstanding>35600000</noOfUnitsOutstanding>
      <approxSaleDate>05/09/2024</approxSaleDate>
      <securitiesExchangeName>NYSE</securitiesExchangeName>
    </securitiesInformation>
    <securitiesToBeSold>
      <securitiesClassTitle>Common</securitiesClassTitle>
      <acquiredDate>04/24/2024</acquiredDate>
      <natureOfAcquisitionTransaction>Restricted Stock Unit</natureOfAcquisitionTransaction>
      <nameOfPersonfromWhomAcquired>Issuer</nameOfPersonfromWhomAcquired>
      <isGiftTransaction>N</isGiftTransaction>
      <amountOfSecuritiesAcquired>1000</amountOfSecuritiesAcquired>
      <paymentDate>04/24/2024</paymentDate>
      <natureOfPayment>Equity Compensation</natureOfPayment>
    </securitiesToBeSold>
    <nothingToReportFlagOnSecuritiesSoldInPast3Months>Y</nothingToReportFlagOnSecuritiesSoldInPast3Months>
    <remarks>Anne Arvia joint owner John &amp; Anne Arvia Jt Ten account</remarks>
    <noticeSignature>
      <noticeDate>05/09/2024</noticeDate>
      <signature>Anne L Arvia</signature>
    </noticeSignature>
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144
0001374429
XXXXXXXX
LIVE
0000040211
GATX CORP
001-02328
233 SOUTH WACKER DRIVE
CHICAGO
IL
60606-7147
3126216200
Arvia Anne L
Director
Common
Charles Schwan Corporation
3000 Schwab Way
Westlake
TX
76262
1000
132450.00
35600000
05/09/2024
NYSE
Common
04/24/2024
Restricted Stock Unit
Issuer
N
1000
04/24/2024
Equity Compensation
Y
Anne Arvia joint owner John & Anne Arvia Jt Ten account
05/09/2024
Anne L Arvia