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

    <schemaVersion>X0206</schemaVersion>

    <documentType>3/A</documentType>

    <periodOfReport>2020-02-27</periodOfReport>

    <dateOfOriginalSubmission>2020-03-02</dateOfOriginalSubmission>

    <noSecuritiesOwned>0</noSecuritiesOwned>

    <issuer>
        <issuerCik>0000923571</issuerCik>
        <issuerName>US XPRESS ENTERPRISES INC</issuerName>
        <issuerTradingSymbol>USX</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001804576</rptOwnerCik>
            <rptOwnerName>Gard Joel</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>4080 JENKINS ROAD</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>CHATTANOOGA</rptOwnerCity>
            <rptOwnerState>TN</rptOwnerState>
            <rptOwnerZipCode>37421</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Pres., Digital Transformation</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Class A Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>31822</value>
                    <footnoteId id="F1"/>
                    <footnoteId id="F2"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">This line is being amended to show that the Reporting Person's total direct beneficial ownership of the issuer's Class A Common Stock as of February 27, 2020 was 31,822 shares, instead of 21,822 shares. The additional 10,000 shares also were omitted from the Form 4 filed by the Reporting Person on March 2, 2020. Accordingly, following the Reporting Person's February 27, 2020 acquisition reported on such Form 4, the Reporting Person directly held 33,022 shares.</footnote>
        <footnote id="F2">Includes 21,483 shares of restricted stock that will vest in four approximately equal installments on each of February 26, 2021, 2022, 2023, and 2024 and are subject to certain vesting, forfeiture, and termination provisions.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Joel Gard, by Heidi Hornung-Scherr, attorney-in-fact, pursuant to a POA previously filed with the SEC</signatureName>
        <signatureDate>2020-03-24</signatureDate>
    </ownerSignature>
</ownershipDocument>
