<SEC-DOCUMENT>0000899243-21-006438.txt : 20210212
<SEC-HEADER>0000899243-21-006438.hdr.sgml : 20210212
<ACCEPTANCE-DATETIME>20210212210028
ACCESSION NUMBER:		0000899243-21-006438
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20210210
FILED AS OF DATE:		20210212
DATE AS OF CHANGE:		20210212

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Hilal Paul C
		CENTRAL INDEX KEY:			0001413084

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-08022
		FILM NUMBER:		21631475

	MAIL ADDRESS:	
		STREET 1:		PERSHING SQUARE CAPITAL MANAGEMENT, L.P.
		STREET 2:		888 SEVENTH AVENUE, 29TH FLOOR
		CITY:			NEW YORK
		STATE:			NY
		ZIP:			10019

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			CSX CORP
		CENTRAL INDEX KEY:			0000277948
		STANDARD INDUSTRIAL CLASSIFICATION:	RAILROADS, LINE-HAUL OPERATING [4011]
		IRS NUMBER:				621051971
		STATE OF INCORPORATION:			VA
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		500 WATER STREET
		STREET 2:		15TH FLOOR
		CITY:			JACKSONVILLE
		STATE:			FL
		ZIP:			32202
		BUSINESS PHONE:		9043593200

	MAIL ADDRESS:	
		STREET 1:		500 WATER STREET
		STREET 2:		15TH FLOOR
		CITY:			JACKSONVILLE
		STATE:			FL
		ZIP:			32202
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>doc4.xml
<DESCRIPTION>FORM 4 SUBMISSION
<TEXT>
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<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2021-02-10</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000277948</issuerCik>
        <issuerName>CSX CORP</issuerName>
        <issuerTradingSymbol>CSX</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001413084</rptOwnerCik>
            <rptOwnerName>Hilal Paul C</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>712 FIFTH AVENUE, SUITE 17F</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>NEW YORK</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10019</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2021-02-10</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>1910</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>88.18</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>12399</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2021-02-12</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>J</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
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            <transactionTimeliness>
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                <transactionShares>
                    <value>85000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F2"/>
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                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>2515079</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See footnotes</value>
                    <footnoteId id="F3"/>
                    <footnoteId id="F4"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2021-02-12</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>G</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F5"/>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>5743</value>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F5"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>2509336</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See footnote</value>
                    <footnoteId id="F5"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Exempt payment of director's fees and/or annual retainer in the form of CSX Common Stock pursuant to the 2019 CSX Stock and Incentive Award Plan.</footnote>
        <footnote id="F2">Reflects distributions by MR Employee Incentive Pool LLC, an entity controlled by Paul C. Hilal and which holds shares of the Issuer on behalf of certain employees of Mantle Ridge LP, a Delaware limited partnership, to those employees. No consideration was paid in connection with these distributions.</footnote>
        <footnote id="F3">By virtue of Mr. Hilal's position as ultimately controlling various entities that hold shares in the Issuer, Mr. Hilal may be deemed to be the beneficial owner of these shares for purposes of Rule 16a-1(a) under the Securities Exchange Act of 1934 (the &quot;Exchange Act&quot;). Mr. Hilal disclaims beneficial ownership of any of these shares, except to the extent of any pecuniary interest therein.</footnote>
        <footnote id="F4">Mr. Hilal continues to serve as a director and as Vice Chairman of the Board of the Issuer and as a result, the entities listed in these notes are directors by deputization for purposes of Section 16 of the Exchange Act.</footnote>
        <footnote id="F5">Reflects shares contributed by Mr. Hilal to certain charitable organizations.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ Paul C. Hilal</signatureName>
        <signatureDate>2021-02-12</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
