<SEC-DOCUMENT>0001562180-24-000816.txt : 20240130
<SEC-HEADER>0001562180-24-000816.hdr.sgml : 20240130
<ACCEPTANCE-DATETIME>20240130174745
ACCESSION NUMBER:		0001562180-24-000816
CONFORMED SUBMISSION TYPE:	3
PUBLIC DOCUMENT COUNT:		2
CONFORMED PERIOD OF REPORT:	20240126
FILED AS OF DATE:		20240130
DATE AS OF CHANGE:		20240130

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Holmes John McClain III
		CENTRAL INDEX KEY:			0001554880
		ORGANIZATION NAME:           	

	FILING VALUES:
		FORM TYPE:		3
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-02328
		FILM NUMBER:		24579868

	MAIL ADDRESS:	
		STREET 1:		1100 N. WOOD DALE ROAD
		CITY:			WOOD DALE
		STATE:			IL
		ZIP:			60191

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			GATX CORP
		CENTRAL INDEX KEY:			0000040211
		STANDARD INDUSTRIAL CLASSIFICATION:	TRANSPORTATION SERVICES [4700]
		ORGANIZATION NAME:           	01 Energy & Transportation
		IRS NUMBER:				361124040
		STATE OF INCORPORATION:			NY
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		233 SOUTH WACKER DRIVE
		CITY:			CHICAGO
		STATE:			IL
		ZIP:			60606-7147
		BUSINESS PHONE:		3126216200

	MAIL ADDRESS:	
		STREET 1:		233 SOUTH WACKER DRIVE
		CITY:			CHICAGO
		STATE:			IL
		ZIP:			60606-7147

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	GENERAL AMERICAN TRANSPORTATION CORP
		DATE OF NAME CHANGE:	19750722
</SEC-HEADER>
<DOCUMENT>
<TYPE>3
<SEQUENCE>1
<FILENAME>primarydocument.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0206</schemaVersion>

    <documentType>3</documentType>

    <periodOfReport>2024-01-26</periodOfReport>

    <noSecuritiesOwned>0</noSecuritiesOwned>

    <issuer>
        <issuerCik>0000040211</issuerCik>
        <issuerName>GATX CORP</issuerName>
        <issuerTradingSymbol>GATX</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001554880</rptOwnerCik>
            <rptOwnerName>Holmes John McClain III</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>1100 N. WOOD DALE RD.</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>WOOD DALE</rptOwnerCity>
            <rptOwnerState>IL</rptOwnerState>
            <rptOwnerZipCode>60191</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>true</isDirector>
            <isOfficer>false</isOfficer>
            <isTenPercentOwner>false</isTenPercentOwner>
            <isOther>false</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>0.00</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes></footnotes>

    <remarks>Exhibit List:

Exhibit 1 - Confirming Statement</remarks>

    <ownerSignature>
        <signatureName>Lisa M. Ibarra, by Power of Attorney on behalf of John M. Holmes</signatureName>
        <signatureDate>2024-01-30</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
<DOCUMENT>
<TYPE>EX-24
<SEQUENCE>2
<FILENAME>jmh-confirmingstatement.txt
<DESCRIPTION>CONFIRMING STATEMENT JMH
<TEXT>
Exhibit 1

CONFIRMING STATEMENT



This Statement confirms that the undersigned, John M. Holmes,
has authorized and designated Brian L. Glassberg, Alan R.
Haguewood and Lisa M. Ibarra to execute and file on the
undersigneds behalf all Forms 3, 4 and 5 (including any
amendments thereto) that the undersigned may be required to file
with the U.S. Securities and Exchange Commission as a result of
the undersigneds ownership of or transactions in securities of
GATX Corporation.  The authority of Brian L. Glassberg, Alan R.
Haguewood and Lisa M. Ibarra under this Statement shall continue
until the undersigned is no longer required to file Forms 3, 4
and 5 with regard to the undersigneds ownership of or
transactions in securities of GATX Corporation, unless earlier
revoked in writing.  The undersigned acknowledges that neither
Brian L. Glassberg, nor Alan R. Haguewood nor Lisa M. Ibarra is
assuming any of the undersigneds responsibilities to comply
with Section 16 of the Securities Exchange Act of 1934.




Date: December 20, 2023


/s/ John M. Holmes
John M. Holmes
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
