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

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2016-07-13</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001513965</issuerCik>
        <issuerName>American Midstream Partners, LP</issuerName>
        <issuerTradingSymbol>AMID</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001526581</rptOwnerCik>
            <rptOwnerName>Energy Spectrum Securities Corp</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>5956 SHERRY LN STE 900</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>DALLAS</rptOwnerCity>
            <rptOwnerState>TX</rptOwnerState>
            <rptOwnerZipCode>75225</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001623040</rptOwnerCik>
            <rptOwnerName>Energy Spectrum Capital VI LP</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>5956 SHERRY LANE, SUITE 900</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>DALLAS</rptOwnerCity>
            <rptOwnerState>TX</rptOwnerState>
            <rptOwnerZipCode>75225</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001623042</rptOwnerCik>
            <rptOwnerName>Energy Spectrum VI LLC</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>5956 SHERRY LANE, SUITE 900</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>DALLAS</rptOwnerCity>
            <rptOwnerState>TX</rptOwnerState>
            <rptOwnerZipCode>75225</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001504801</rptOwnerCik>
            <rptOwnerName>Energy Spectrum Partners VI LP</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>5956 SHERRY LANE</rptOwnerStreet1>
            <rptOwnerStreet2>SUITE 900</rptOwnerStreet2>
            <rptOwnerCity>DALLAS</rptOwnerCity>
            <rptOwnerState>TX</rptOwnerState>
            <rptOwnerZipCode>75225</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Units</value>
            </securityTitle>
            <transactionDate>
                <value>2016-07-13</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>29900</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>12.1897</value>
                    <footnoteId id="F2"/>
                    <footnoteId id="F4"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>5289963</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See footnote.</value>
                    <footnoteId id="F1"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Units</value>
            </securityTitle>
            <transactionDate>
                <value>2016-07-14</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>21964</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>12.1017</value>
                    <footnoteId id="F3"/>
                    <footnoteId id="F4"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>5267999</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See footnote.</value>
                    <footnoteId id="F1"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Energy Spectrum Securities Corporation (&quot;ESSC&quot;) owns 100% of the issued and outstanding membership interest of Energy Spectrum VI, LLC, a Texas limited liability company (&quot;ESLLC&quot;), which serves as the general partner of Energy Spectrum Capital VI LP, a Delaware limited partnership (&quot;ESCLP&quot;), which serves as the general partner of Energy Spectrum Partners VI LP, a Delaware limited partnership (&quot;ESP&quot; and together with ESSC, ESLLC, and ESCLP, the &quot;Reporting Persons&quot;).  ESP is the record holder of the Common Units of the Issuer (&quot;Units&quot;) reported in this line on this Form 4 and has a direct pecuniary interest in the Units.  ESSC, ESLLC, and ESCLP beneficially own the Units for the purposes of Section 13(d) of the Exchange Act and have an indirect pecuniary interest in the Units.</footnote>
        <footnote id="F2">On July 13, 2016, ESP sold 29,900 Units on the New York Stock Exchange in open market sales, at prices ranging from $12.15 to $12.46 per Unit, with a weighted-average per-Unit price of $12.1897.</footnote>
        <footnote id="F3">On July 14, 2016, ESP sold 21,964 Units on the New York Stock Exchange in open market sales, at prices ranging from $12.02 to $12.20 per Unit, with a weighted-average per-Unit price of $12.1017.</footnote>
        <footnote id="F4">The Reporting Persons agree to provide, upon request by the Securities Exchange Commission, the Issuer, or a holder of Units, full information regarding the number of units sold at each separate price.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>James P. Benson</signatureName>
        <signatureDate>2016-07-15</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>James P. Benson</signatureName>
        <signatureDate>2016-07-15</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>James P. Benson</signatureName>
        <signatureDate>2016-07-15</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>James P. Benson</signatureName>
        <signatureDate>2016-07-15</signatureDate>
    </ownerSignature>
</ownershipDocument>
