<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0508</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2023-11-21</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

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

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001764389</rptOwnerCik>
            <rptOwnerName>Vena Vincenzo J</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>1400 DOUGLAS STREET</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>OMAHA</rptOwnerCity>
            <rptOwnerState>NE</rptOwnerState>
            <rptOwnerZipCode>68179</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>CHIEF EXECUTIVE OFFICER</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <aff10b5One>1</aff10b5One>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
                <footnoteId id="F1"/>
            </securityTitle>
            <transactionDate>
                <value>2023-11-21</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F2"/>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>4500</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>222.0016</value>
                    <footnoteId id="F3"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>5106.4381</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">This Form 4 filing was posted to the issuer's website on November 22, 2023, but as a result of an administrative error was not filed with the Securities and Exchange Commission until December 11, 2023. This form reports the purchase of all 4,500 shares purchased pursuant to the reporting person's Rule 10b5-1 trading arrangement, the terms of which were previously disclosed in Part II, Item 5 of the issuer's Quarterly Report on Form 10-Q for the quarter ended September 30, 3023.</footnote>
        <footnote id="F2">This transaction was made pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on August 22, 2023.</footnote>
        <footnote id="F3">This transaction was executed in multiple trades at prices ranging from $219.61 to $222.87. The price reported above reflects the weighted average purchase price. The reporting person hereby undertakes to provide upon request to the SEC staff, the issuer or a security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>By: Trevor L. Kingston, Attorney-in-Fact For: Vincenzo J. Vena</signatureName>
        <signatureDate>2023-12-11</signatureDate>
    </ownerSignature>
</ownershipDocument>
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X0508
4
2023-11-21
0
0000100885
UNION PACIFIC CORP
UNP
0001764389
Vena Vincenzo J
1400 DOUGLAS STREET
OMAHA
NE
68179
1
1
0
0
CHIEF EXECUTIVE OFFICER
1
Common Stock
2023-11-21
4
P
0
4500
222.0016
A
5106.4381
D
This Form 4 filing was posted to the issuer's website on November 22, 2023, but as a result of an administrative error was not filed with the Securities and Exchange Commission until December 11, 2023. This form reports the purchase of all 4,500 shares purchased pursuant to the reporting person's Rule 10b5-1 trading arrangement, the terms of which were previously disclosed in Part II, Item 5 of the issuer's Quarterly Report on Form 10-Q for the quarter ended September 30, 3023.
This transaction was made pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on August 22, 2023.
This transaction was executed in multiple trades at prices ranging from $219.61 to $222.87. The price reported above reflects the weighted average purchase price. The reporting person hereby undertakes to provide upon request to the SEC staff, the issuer or a security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected.
By: Trevor L. Kingston, Attorney-in-Fact For: Vincenzo J. Vena
2023-12-11