-----BEGIN PRIVACY-ENHANCED MESSAGE-----
Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
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 TWSM7vrzLADbmYQaionwg5sDW3P6oaM5D3tdezXMm7z1T+B+twIDAQAB
MIC-Info: RSA-MD5,RSA,
 N7VOzuRLOFZTaDRAt4Cbl20RkuMer7Jj6rqURn6pcpbQmEbnR2nTVt6NIZYEJ0pV
 lHuBsaGNef22HM1zchQZTA==

<SEC-DOCUMENT>0000100885-03-000017.txt : 20030616
<SEC-HEADER>0000100885-03-000017.hdr.sgml : 20030616
<ACCEPTANCE-DATETIME>20030616162341
ACCESSION NUMBER:		0000100885-03-000017
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20030611
FILED AS OF DATE:		20030616

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			DOLAN JAMES V
		CENTRAL INDEX KEY:			0001199999

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-06075
		FILM NUMBER:		03745790

	MAIL ADDRESS:	
		STREET 1:		UNION PACIFIC CORP
		STREET 2:		1416 DODGE ST
		CITY:			OMAHA
		STATE:			NE
		ZIP:			68179

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			UNION PACIFIC CORP
		CENTRAL INDEX KEY:			0000100885
		STANDARD INDUSTRIAL CLASSIFICATION:	RAILROADS, LINE-HAUL OPERATING [4011]
		IRS NUMBER:				132626465
		STATE OF INCORPORATION:			UT
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		1416 DODGE STREET
		STREET 2:		ROOM 830
		CITY:			OMAHA
		STATE:			NE
		ZIP:			68179
		BUSINESS PHONE:		402 271 5213

	MAIL ADDRESS:	
		STREET 1:		1416 DODGE STREET
		STREET 2:		ROOM 830
		CITY:			OMAHA
		STATE:			NE
		ZIP:			68179
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>primary_doc.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>

<ownershipDocument>

    <documentType>4</documentType>

    <periodOfReport>2003-06-11</periodOfReport>


    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000100885</issuerCik>
        <issuerName>UNION PACIFIC CORP</issuerName>
        <issuerTradingSymbol>UNP</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001199999</rptOwnerCik>
            <rptOwnerName>DOLAN JAMES V</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>  </rptOwnerStreet1>
            <rptOwnerStreet2>  </rptOwnerStreet2>
            <rptOwnerCity>  </rptOwnerCity>
            <rptOwnerState>  </rptOwnerState>
            <rptOwnerZipCode>  </rptOwnerZipCode>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Vice Chairman</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeSecurity>
        <securityTitle>
            <value>Common Stock</value>
        </securityTitle>
        <transactionDate>
            <value>2003-06-11</value>
        </transactionDate>
        <transactionCoding>
            <transactionFormType>4</transactionFormType>
            <transactionCode>I</transactionCode>
            <equitySwapInvolved>0</equitySwapInvolved>
        </transactionCoding>
        <transactionTimeliness>
            <value></value>
        </transactionTimeliness>
        <transactionAmounts>
            <transactionShares>
                <value>3168.5164</value>
            </transactionShares>
            <transactionValue>
                <value>60.85</value>
            </transactionValue>
            <transactionAcquiredDisposedCode>
                <value>D</value>
            </transactionAcquiredDisposedCode>
        </transactionAmounts>
        <postTransactionAmounts>
            <sharesOwnedFollowingTransaction>
                <value>107.9806</value>
                <footnoteId id="F1"/>
            </sharesOwnedFollowingTransaction>
        </postTransactionAmounts>
        <ownershipNature>
            <directOrIndirectOwnership>
                <value>I</value>
            </directOrIndirectOwnership>
            <natureOfOwnership>
                <value>by Managed Account</value>
            </natureOfOwnership>
        </ownershipNature>
    </nonDerivativeSecurity>

    <footnotes>
        <footnote id="F1">Includes holdings in Union Pacific's Payroll Based Stock Ownership Plan as of the Transaction Date.  The reporting person also has the following holdings: 1) 650 shares held indirectly by the reporting person's spouse, and the reporting person disclaims beneficial ownership of these securities except to the extent of his pecuniary interest therein; and 2) 102,458 shares held directly by the reporting person.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>James V. Dolan</signatureName>
        <signatureDate>2003-06-16</signatureDate>
    </ownerSignature>

</ownershipDocument>

</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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