QUESTIONS AND ANSWERS ABOUT THE MERGER AND THE SPECIAL MEETING

General Questions and Answers

Set forth below are questions that you, as a unitholder of JPE, may have regarding the Merger, the Adjournment Proposal, the Advisory Compensation Proposal and the Special Meeting, and brief answers to those questions. You are urged to read carefully this proxy statement/prospectus and the other documents referred to in this proxy statement/prospectus in their entirety, including the Merger Agreement, which is attached as Annex A to this proxy statement/prospectus, and the documents incorporated by reference into this proxy statement/prospectus, because this section may not provide all of the information that is important to you with respect to the Merger and the Special Meeting. You may obtain a list of the documents incorporated by reference into this proxy statement/prospectus in the section titled “Where You Can Find More Information.”

In the Merger, AMID will issue AMID Common Units as the consideration to be paid to the holders of JPE Common Units and JPE Subordinated Units. This document is being delivered to you as both a proxy statement of JPE and a prospectus of AMID in connection with the Merger. It is the proxy statement by which the JPE GP Board is soliciting proxies from you to vote on the adoption of the Merger Agreement and the transactions contemplated thereby at the Special Meeting or at any adjournment or postponement of the Special Meeting. It is also the prospectus by which AMID will issue AMID Common Units to you in the Merger.

The approval of the Merger Proposal by JPE Unitholders is a condition to the obligations of AMID and JPE to complete the Merger. Neither the Adjournment Proposal nor the Advisory Compensation Proposal is a condition to the obligations of AMID or JPE to complete the Merger.

Simultaneous with the execution of the Merger Agreement, AMID and AMID GP entered into a Support Agreement, dated as of October 23, 2016, with certain executive officers and directors of JPE GP (the “Management Support Agreement”). Pursuant to the Management Support Agreement, such executive officers and directors have agreed to vote all of their JPE Units (to the extent such JPE Units are entitled to vote) in favor of the Merger Proposal and any other matter necessary for the consummation of the Merger.

For purposes of determining whether the Merger Agreement and the Merger have been approved and adopted by the Non-Affiliated JPE Common Units, JPE Common Units held by directors and executive officers of JPE GP and their affiliates will not be counted toward the required majority vote of outstanding Non-Affiliated JPE Common Units.

As of the record date of the Special Meeting, the Affiliated Unitholders owned, in the aggregate, 14,992,654 JPE Subordinated Units, or collectively approximately 82.7% of the outstanding JPE Subordinated Units entitled to vote at the Special Meeting. Simultaneous with the execution of the Merger Agreement, AMID and AMID GP entered into a Support Agreement, dated as of October 23, 2016, with Magnolia Infrastructure Holdings, LLC, a Delaware limited liability company (“Magnolia”), which is an affiliate of ArcLight Capital (defined below), and the Affiliated Unitholders (the “Affiliated Unitholder Support Agreement” and, together with the Management Support Agreement, the “Support Agreements”). Pursuant to the Affiliated Unitholder Support Agreement, each of Magnolia and the Affiliated Unitholders has agreed to vote all of its JPE Subordinated Units in favor of the Merger Proposal and any other matter necessary for the consummation of the Merger.

Pursuant to the Support Agreements, Magnolia, the Affiliated Unitholders and certain members of JPE management, which collectively own 90.1% of the JPE Subordinated Units entitled to vote at the Special Meeting, have agreed to vote all of such JPE Subordinated Units in favor of approval of the Merger Proposal and any other matter necessary for the consummation of the Merger.

Even if you plan to attend the Special Meeting in person, you are encouraged to submit your proxy as described above so that your vote will be counted if you later decide not to attend the Special Meeting.

If your JPE Units are held by a broker, bank or other nominee, also known as holding units in “street name,” you should receive instructions from the broker, bank or other nominee that you must follow in order to have your JPE Units voted. Please review such instructions to determine whether you will be able to vote via the Internet or by telephone. The deadline for voting JPE Units by telephone or electronically through the Internet is 11:59 p.m. Eastern Time on                 ,          (the “telephone/internet deadline”).

If you do not provide voting instructions to your broker, your JPE Units will not be voted on any proposal on which your broker does not have discretionary authority to vote. This is referred to in this proxy statement/prospectus and in general as a broker non-vote. In these cases, the broker can register your JPE Units as being present at the Special Meeting for purposes of determining a quorum, but will not be able to vote on those matters for which specific authorization is required. Under the current rules of the NYSE, brokers do not have discretionary authority to vote on any of the proposals, including the Merger Proposal. A broker non-vote will have the same effect as a vote “AGAINST” the Merger Proposal, the Adjournment Proposal and the Advisory Compensation Proposal.

If you hold your JPE Units through a broker or other nominee, you must follow the directions you receive from your broker or other nominee in order to revoke your proxy or change your voting instructions.

JPE Unitholders are urged to read the discussion in the section entitled “Material U.S. Federal Income Tax Consequences of the Merger” beginning on page 117 of this proxy statement/prospectus for a more complete discussion of the U.S. federal income tax consequences of the Merger and to consult their tax advisors as to the U.S. federal income tax consequences of the transaction, as well as the effects of state, local and non-U.S. tax laws.

JPE expects to furnish a Schedule K-1 to each JPE Unitholder within 90 days of the end of the calendar year in which the closing of the Merger occurs, and AMID expects to furnish a Schedule K-1 to each holder of AMID Common Units (the “AMID Unitholders”) within 90 days of the closing of AMID’s taxable year on December 31, 2017.

If you hold JPE Units through a broker or other nominee, please instruct your broker or nominee to vote your JPE Units by following the instructions that the broker or nominee provides to you with these materials.

SUMMARY

The following is a summary of the information contained in this proxy statement/prospectus relating to the Merger. This summary may not contain all of the information about the Merger that is important to you. For a more complete description of the Merger, AMID and JPE encourage you to read carefully this entire proxy statement/prospectus, including the attached annexes. In addition, AMID and JPE encourage you to read the information incorporated by reference into this proxy statement/prospectus, which includes important business and financial information about AMID and JPE. JPE Unitholders may obtain the information incorporated by reference into this proxy statement/prospectus without charge by following the instructions in the section entitled “Where You Can Find More Information” beginning on page 203 of this proxy statement/prospectus.

The Merger

AMID and JPE have agreed to combine their businesses under the terms of the Merger Agreement that is described in this proxy statement/prospectus. Under the terms of the Merger Agreement, a wholly owned subsidiary of AMID will merge with and into JPE, with JPE surviving as a wholly owned subsidiary of AMID. Upon completion of the Merger, holders of JPE Common Units and JPE Subordinated Units other than Affiliated Unitholders and GP Sub will be entitled to receive 0.5775 of an AMID Common Unit for each JPE Common Unit and each JPE Subordinated Unit held. Each Affiliated Unitholder will be entitled to receive 0.5225 of an AMID Common Unit for each JPE Common Unit and each JPE Subordinated Unit held by such Affiliated Unitholder. The resulting weighted average exchange ratio will be approximately 0.55 AMID Common Units for each JPE Unit. GP Sub will continue to own 0.1% of the outstanding limited partner interest in JPE after the closing of the Merger. As a result of the transactions contemplated by the Merger Agreement, including the Merger, former holders of JPE Units will own AMID Common Units. AMID Unitholders will continue to own their existing AMID Common Units after the Merger.

The Merger Agreement is attached as Annex A to this proxy statement/prospectus. We encourage you to read the Merger Agreement because it is the legal document that governs the terms and conditions of the Merger.

The GP Merger

Immediately prior to and as a condition to the Merger, a wholly owned subsidiary of AMID GP will merge with and into JPE GP, with JPE GP surviving as a wholly owned subsidiary of AMID GP. In connection with the GP Merger, GP Sub, a wholly owned subsidiary of AMID, will be admitted as the sole general partner of JPE and JPE GP will simultaneously cease to be the general partner of JPE. At the effective time of the GP Merger, the membership interests in JPE GP issued and outstanding immediately prior to the effective time of the GP Merger will be converted into a right to receive Class A Membership Interests (as defined in the AMID LLC Agreement), representing a Sharing Percentage (as defined in the AMID LLC Agreement) of 18.786%.

Parties to the Mergers (see page 50)

AMERICAN MIDSTREAM PARTNERS, LP

AMID is a growth-oriented Delaware limited partnership that was formed in August 2009 to own, operate, develop and acquire a diversified portfolio of midstream energy assets. It is engaged in the business of gathering, treating, processing, and transporting natural gas; gathering, transporting, storing, treating and fractionating NGLs; gathering, storing and transporting crude oil and condensates; and storing specialty chemical products, all

through its ownership and operation of twelve gathering systems, five processing facilities, three fractionation facilities, three marine terminal sites, three interstate pipelines, five intrastate pipelines and one crude oil pipeline.

AMERICAN MIDSTREAM GP, LLC

AMID GP is the general partner of AMID. Its board of directors (the “AMID GP Board”) and executive officers manage AMID. AMID GP is 95% owned by High Point Infrastructure Partners, LLC (“HPIP”), an affiliate of ArcLight Capital Partners, LLC (“ArcLight Capital”), and 5% owned by Magnolia, which acquired AIM Midstream Holdings, LLC’s (“AIM”) interest in AMID GP. Through HPIP, ArcLight Capital controls AMID GP. AMID holds assets primarily in a number of wholly owned limited liability companies, two limited partnerships and a corporation.

Argo Merger Sub, LLC

c/o American Midstream Partners, LP

Argo Merger Sub, LLC, a Delaware limited liability company and a wholly owned subsidiary of AMID, was formed solely for the purpose of facilitating the Merger. AMID Merger Sub has not carried on any activities or operations to date, except for those activities incidental to its formation and undertaken in connection with the transactions contemplated by the Merger Agreement. By operation of the Merger, AMID Merger Sub will be merged with and into JPE, with JPE surviving the Merger as a wholly owned subsidiary of AMID.

Argo GP Sub, LLC

c/o American Midstream Partners, LP

Argo GP Sub, LLC, a Delaware limited liability company and a wholly owned subsidiary of AMID GP, was formed solely for the purpose of facilitating the GP Merger. Merger Sub GP has not carried on any activities or operations to date, except for those activities incidental to its formation and undertaken in connection with the transactions contemplated by the GP Merger Agreement. By operation of the GP Merger, Merger Sub GP will be merged with and into JPE GP, with JPE GP surviving the GP Merger as a wholly owned subsidiary of AMID GP.

ARGO MERGER GP SUB, LLC

c/o American Midstream Partners, LP

Argo Merger GP Sub, LLC, a Delaware limited liability company and a wholly owned subsidiary of AMID, was formed solely for the purpose of acquiring 0.1% of the issued and outstanding JPE Common Units and becoming the sole general partner of JPE following the Merger. GP Sub has not carried on any activities or

operations to date, except for those activities incidental to its formation and undertaken in connection with the transactions contemplated by the Merger Agreement. In connection with the Mergers, GP Sub will be admitted as the sole general partner of JPE. GP Sub will continue to own 0.1% of the outstanding limited partner interests in JPE after the closing of the Merger.

JP ENERGY PARTNERS LP

600 East Las Colinas Blvd, Suite 2000

Irving, Texas 75039

Phone: (972) 444-0300

JPE is a growth-oriented limited partnership formed in May 2010 by members of its management and further capitalized by ArcLight Energy Partners Fund V, L.P. (“ArcLight”) to own, operate, develop and acquire a diversified portfolio of midstream energy assets. JPE’s operations currently consist of three business segments: (i) crude oil pipelines and storage, (ii) refined products terminals and storage and (iii) NGL distribution and sales. Together its businesses provide midstream infrastructure solutions for the growing supply of crude oil, refined products and NGLs in the United States. JPE’s primary business strategy is to focus on (i) owning, operating and developing midstream assets serving two of the most prolific shale plays in the United States, as well as serving key crude oil, refined product and NGL distribution hubs and (ii) providing midstream infrastructure solutions to users of liquid petroleum products in order to capitalize on changing product flows between producing and consuming markets resulting from the growth in hydrocarbon production across the United States.

JP ENERGY GP II LLC

600 East Las Colinas Blvd, Suite 2000

Irving, Texas 75039

(972) 444-0300

JPE GP is the general partner of JPE. Its board of directors and executive officers manage JPE, and AL Lonestar owns and controls JPE GP. ArcLight Capital manages ArcLight, which controls JPE GP through its ownership and control of AL Lonestar.

Merger Consideration (see page 94)

The Merger Agreement provides that, at the Effective Time, each JPE Unit issued and outstanding or deemed issued and outstanding as of immediately prior to the Effective Time (other than JPE Units held by Affiliated Unitholders or GP Sub) will be converted into the right to receive 0.5775 AMID Common Units and (ii) each JPE Unit issued and outstanding or deemed issued and outstanding as of immediately prior to the Effective Time held by the Affiliated Unitholders will be converted into the right to receive 0.5225 AMID Common Units. The JPE Units held by GP Sub will remain outstanding in JPE, and GP Sub will continue as a limited partner of JPE.

Treatment of General Partner Interest and Incentive Distribution Rights (see page 94)

As a result of the Merger, the general partner interest in JPE outstanding immediately prior to the Effective Time will be cancelled and cease to exist and no consideration will be delivered in exchange for such JPE general partner interest and GP Sub will be admitted as the sole general partner of the surviving entity. In addition, the incentive distribution rights in JPE outstanding immediately prior to the Effective Time will be cancelled.

Treatment of JPE Equity-Based Awards (see page 94)

Each award of JPE Phantom Units that is outstanding immediately prior to the Effective Time, automatically and without any action on the part of the holder of such JPE Phantom Unit, will at the Effective Time be converted into the right to receive an award of phantom units relating to AMID Common Units on the

same terms and conditions as were applicable to the award of JPE Phantom Units, except that the number of AMID Common Units covered by the award will be equal to the number of JPE Common Units covered by the corresponding award of JPE Phantom Units multiplied by the Exchange Ratio.

The JPE Special Unitholder Meeting (see page 53)

Meeting. The Special Meeting will be held at                 , on                     ,                      , at          local time. At the Special Meeting, JPE Unitholders will be asked to vote on the following proposals:

Who Can Vote at the Special Meeting. Only JPE Unitholders of record at the close of business on                 ,              will be entitled to receive notice of and to vote at the Special Meeting. As of the close of business on the record date of                     , 2017, there were              JPE Common Units and 18,122,904 JPE Subordinated Units outstanding and entitled to vote at the Special Meeting. Each holder of JPE Common Units and JPE Subordinated Units is entitled to one vote for each JPE Common Unit or JPE Subordinated Unit owned as of the record date.

Required Vote. The affirmative vote of holders of at least a majority of the outstanding Non-Affiliated JPE Common Units is required to approve and adopt the Merger Agreement and approve the Merger. As of the record date, there were              Non-Affiliated JPE Common Units outstanding. For purposes of determining whether the Merger Agreement and the Merger have been approved and adopted by the Non-Affiliated JPE Common Units, JPE Common Units held by directors and officers of JPE GP and their affiliates will not be counted toward the required majority vote of outstanding Non-Affiliated JPE Common Units. The affirmative vote of a majority of the Non-Affiliated JPE Common Units would be deemed to approve the Merger for all purposes of Section 7.9(a) of the JPE partnership agreement. The affirmative vote of holders of at least a majority of the outstanding JPE Subordinated Units is also required to approve and adopt the Merger Agreement and approve the Merger. The Affiliated Unitholders and certain members of JPE management, which collectively own 90.1% of the JPE Subordinated Units entitled to vote at the Special Meeting, have agreed to vote all of such JPE Subordinated Units in favor of approval of the Merger Proposal and any other matter necessary for the consummation of the Merger.

The affirmative vote of holders of at least a majority of the outstanding JPE Common Units is required to approve the adjournment of the Special Meeting, if necessary, to solicit additional proxies if there are not sufficient votes to adopt and approve the Merger Agreement and the transactions contemplated thereby, including the Merger, at the time of the Special Meeting if a quorum is present at the meeting; provided that, if a quorum is not present at the meeting, the affirmative vote of holders of a majority of the outstanding JPE Common Units entitled to vote at such meeting represented either in person or by proxy is required to approve the proposal.

The affirmative vote of holders of at least a majority of the outstanding JPE Common Units is required to approve, on an advisory (non-binding) basis, the compensation that may be paid or become payable to JPE’s named executive officers in connection with the Merger.

Abstentions will have the same effect as votes “AGAINST” approval and if you fail to cast your vote in person or by proxy or fail to give voting instructions to your broker, bank or other nominee and are otherwise represented in person or by proxy, it will have the same effect as a vote “AGAINST” the proposal.

Unit Ownership of and Voting by JPE’s Directors, Executive Officers and Affiliates. For purposes of determining whether the Merger Agreement and the Merger have been approved and adopted by the Non-Affiliated JPE Common Units, JPE Common Units held by directors and executive officers of JPE GP and their affiliates will not be counted.

At the close of business on the record date for the Special Meeting, JPE GP’s directors and executive officers and their affiliates (including the Affiliated Unitholders) beneficially owned 16,334,997 JPE Subordinated Units, which represent approximately 90.1% of the JPE Subordinated Units entitled to vote at the Special Meeting, and have agreed to vote all of such JPE Subordinated Units in favor of approval of the Merger Proposal and any other matter necessary for the consummation of the Merger.

JPE GP Board Recommendations and Reasons for the Merger (see page 66)

The JPE GP Board recommends that JPE Unitholders vote “FOR” the approval of the Merger Agreement, that holders of JPE Common Units vote “FOR” the adjournment of the Special Meeting, if necessary to solicit additional proxies if there are not sufficient votes to approve the Merger Agreement at the time of the Special Meeting, and that holders of JPE Common Units vote “FOR” the Advisory Compensation proposal.

In the course of reaching its decision to approve the Merger Agreement and the transactions contemplated by the Merger Agreement, the JPE GP Board considered a number of factors in its deliberations. For a more complete discussion of these factors, see “The Merger—JPE GP Board Recommendations and Reasons for the Merger.”

AMID GP Board’s Approval of the Merger (see page 82)

In connection with the Merger, the AMID GP Board established a conflicts committee consisting of three independent directors (the “AMID Conflicts Committee”) to (i) review and evaluate the Merger and the AMID Transaction Documents (as defined herein) for the purpose of determining whether the Merger is in the best interests of AMID and (ii) determine whether or not to grant special approval to, and recommend that the AMID GP Board approve, the Merger and the AMID Transaction Documents. The AMID Conflicts Committee along with its financial and legal advisors conducted an extensive review and evaluation of the proposed Merger. In the course of reaching its decision to approve the Merger Agreement and the transactions contemplated by the Merger Agreement, the AMID Conflicts Committee and the AMID GP Board considered a number of factors in its deliberations. For a more complete discussion of these items, see “The Merger—AMID GP Board’s Approval of the Merger.”

The Support Agreements (see page 69)

In connection with the Merger Agreement, AMID and AMID GP entered into the Affiliated Unitholder Support Agreement and the Management Support Agreement. Under the Support Agreements, the parties are required to vote their JPE Units (to the extent such JPE Units are entitled to vote), as applicable, in favor of the Merger. At least a majority of the outstanding JPE Subordinated Units voting separately as a class must approve the Merger. The Affiliated Unitholders own 14,992,654 JPE Subordinated Units, representing 82.7% of the total issued and outstanding JPE Subordinated Units. For purposes of determining whether the Merger Agreement and the Merger have been approved and adopted by the Non-Affiliated JPE Common Units, JPE Common Units held by directors and executive officers of JPE GP and their affiliates will not be counted toward the required majority vote of outstanding Non-Affiliated JPE Common Units.

The AMID Distribution Support and Expense Reimbursement Agreement (see page 69)

In connection with the Merger Agreement, Magnolia entered into a Distribution Support and Expense Reimbursement Agreement with AMID and AMID GP (the “Financial Support Agreement”). Under the terms of the Financial Support Agreement, Magnolia agrees to provide quarterly financial support, up to a maximum of $25 million, as necessary, to cause AMID to realize a 5% increase in distributable cash flow per AMID Common Unit as set forth in the Financial Support Agreement. The financial support will continue for eight (8) consecutive quarters following the Effective Time, or if earlier, until $25 million in support has been provided. Magnolia will also reimburse AMID for certain expenses it incurs in connection with post-closing transition during a one (1) year period following the Effective Time. In addition, Magnolia agrees to extinguish all outstanding indebtedness of JPE GP to Magnolia or any of its affiliates. Pursuant to the Financial Support Agreement, the elimination of JPE GP’s indebtedness shall occur prior to the Effective Time and result in no further liability to AMID, including any tax liabilities arising from such elimination. Notwithstanding the foregoing, AMID (subject to prior approval by the AMID Conflicts Committee) and Magnolia may make a determination that Magnolia has satisfied the support obligations by such other methods as AMID and Magnolia determine to be appropriate. A copy of the Financial Support Agreement is attached as Annex C hereto.

The JPE Expense Reimbursement Agreement (see page 69)

In connection with the Merger Agreement, Lonestar Midstream Holdings, LLC, a Delaware limited liability company (“Lonestar”), JPE and JPE GP entered into an Expense Reimbursement Agreement (the “JPE Expense Reimbursement Agreement”) providing that AL Lonestar (as successor in merger to Lonestar) will reimburse, or will pay directly on behalf of, JPE or JPE GP the reasonable costs and expenses incurred by JPE or JPE GP to third parties in connection with the Mergers, including (i) the termination fee pursuant to the Merger Agreement and (ii) all reasonable out-of-pocket legal and financial advisory fees, costs and expenses paid or payable to third parties and incurred in connection with the negotiation, execution and performance of the Merger Agreement and consummation of the Mergers; provided, however, that JPE and JPE GP (subject to prior approval by the conflicts committee of the JPE GP Board) and AL Lonestar may make a determination that AL Lonestar has satisfied the requirements by such other methods as the parties determine to be appropriate.

Opinion of Financial Advisor to the JPE GP Board (see page 69)

In connection with the proposed Merger and related transactions, BMO Capital Markets Corp. (“BMOCM”) delivered a written opinion, dated October 23, 2016, to the JPE GP Board as to the fairness, from a financial point of view and as of the date of the opinion, of the 0.5775x exchange ratio provided for pursuant to the terms and conditions of the Merger Agreement. The full text of BMOCM’s written opinion, dated October 23, 2016, to the JPE GP Board, which describes the assumptions made, procedures followed, matters considered and limitations and qualifications on the review undertaken, is attached as Annex B to this proxy statement/prospectus and is incorporated herein by reference. The description of BMOCM’s opinion set forth in this proxy statement/prospectus is qualified in its entirety by reference to the full text of BMOCM’s opinion. BMOCM’s opinion was prepared at the request and for the benefit and use of the JPE GP Board (in its capacity as such) in connection with its evaluation of the 0.5775x exchange ratio from a financial point of view and BMOCM did not express any opinion on any other terms, aspects or implications of the Merger or any related transactions. BMOCM expressed no opinion as to the relative merits of the Merger or any related transactions or any other transactions or business strategies discussed by the JPE GP Board as alternatives to the Merger or any related transactions or the decision of the JPE GP Board to proceed with the Merger or any related transactions. BMOCM’s opinion did not constitute and is not a recommendation to the JPE GP Board as to any action taken on any aspect of the Merger, related transactions or any other matter. BMOCM’s opinion also does not constitute a recommendation to any security holder as to how such holder should vote or act with respect to the Merger, related transactions or any other matter. 

AMID Unitholder Approval is Not Required

AMID Unitholders are not required to adopt the Merger Agreement or approve the Merger or the issuance of AMID Common Units in connection with the Merger.

Governance Matters After the Merger (see page 82)

No changes are being made to the AMID GP Board in connection with the closing of the Merger.

Ownership of AMID After the Merger (see page 83)

AMID will issue approximately 20.1 million AMID Common Units to JPE Unitholders in the Merger. After the completion of the Merger, it is expected that there will be outstanding approximately 51.4 million AMID Common Units. The AMID Common Units to be issued to the JPE Unitholders in the Merger will represent approximately 27.1% of the outstanding AMID Common Units after the Merger on a fully diluted basis.

Interests of the Directors and Executive Officers of JPE GP in the Merger (see page 83)

JPE’s directors and executive officers have interests in the Merger that are different from, or in addition to, the interests of JPE Unitholders generally. The members of the JPE GP Board were aware of and considered these interests, among other matters, in evaluating and negotiating the Merger Agreement and the Merger, and in recommending to the JPE Unitholders that the Merger Agreement be adopted.

These interests include:

Risks Relating to the Merger and Ownership of AMID Common Units (see page 41)

JPE Unitholders should consider carefully all the risk factors together with all of the other information included or incorporated by reference in this proxy statement/prospectus before deciding how to vote. Risks relating to the Merger and ownership of AMID Common Units are described in the section titled “Risk Factors.” Some of these risks include, but are not limited to, those described below:

Conditions to Consummation of the Merger (see page 88)

AMID and JPE currently expect to complete the Merger in the first quarter of 2017, subject to receipt of required JPE Unitholder and regulatory approvals and clearances and to the satisfaction or waiver of the other conditions to the transactions contemplated by the Merger Agreement described below.

As more fully described in this proxy statement/prospectus, each party’s obligation to complete the transactions contemplated by the Merger Agreement depends on a number of customary closing conditions being satisfied or, where legally permissible, waived, including the following:

The obligation of AMID to effect the Merger is subject to the satisfaction or waiver of the following additional conditions:

The obligation of JPE to effect the Merger is subject to the satisfaction or waiver of the following additional conditions:

Regulatory Approvals and Clearances Required for the Merger (see page 85)

Consummation of the Merger is subject to the expiration or termination of a 30-day waiting period under the HSR Act. On November 10, 2016, AMID and JPE filed Notification and Report Forms with the Antitrust Division of the Department of Justice (the “Antitrust Division”) and the Federal Trade Commission (the “FTC”). The 30-day waiting period expired on December 12, 2016. See “The Merger—Regulatory Approvals and Clearances Required for the Merger.”

Amendment to AMID Partnership Agreement (see page 102)

In connection with the closing of the Merger, AMID GP will enter into an amendment to the AMID partnership agreement (the “AMID Partnership Agreement Amendment”), providing for the payment of series A payment-in-kind (“PIK”) preferred units for the quarter (the “series A preferred quarterly distribution”) in which the Merger is consummated and thereafter equal to the quotient of (i) the greater of (a) $0.4125 and (b) the “series A distribution amount”, as such term is defined in the AMID partnership agreement, divided by (ii) the series A adjusted issue price, as such term is defined in the AMID partnership agreement. However, in the AMID GP’s discretion, which determination shall be made prior to the record date for the relevant quarter, the series A preferred quarterly distribution may be paid as (x) an amount in cash up to the greater of (1) $0.4125 and (2) the series A distribution amount, and (y) a number of series A PIK preferred units equal to the quotient of (a) the remainder of (i) the greater of (I) $0.4125 and (II) the series A distribution amount less (ii) the amount of cash paid pursuant to clause (x), divided by (b) the series A adjusted issue price. See “The Merger—Amendment to AMID Partnership Agreement.”

No Solicitation by JPE of Alternative Proposals (see page 91)

Under the Merger Agreement, JPE has agreed that it will not, and will cause its subsidiaries and use reasonable best efforts to cause its and its subsidiaries’ directors, officers, employees, investment bankers, financial advisors, attorneys, accountants, agents and other representatives not to, directly or indirectly:

In addition, the Merger Agreement requires JPE and its subsidiaries to (i) cease and cause to be terminated any discussions or negotiations with any persons conducted prior to the execution of the Merger Agreement regarding an alternative proposal, (ii) request the return or destruction of all confidential information previously provided to any such persons and (iii) immediately prohibit any access by any persons (other than AMID and its representatives) to any physical or electronic data room relating to a possible alternative proposal.

Notwithstanding these restrictions, the Merger Agreement provides that, under specified circumstances at any time prior to JPE Unitholders voting in favor of adopting the Merger Agreement, JPE may furnish information, including confidential information, with respect to it and its subsidiaries to, and participate in discussions or negotiations with, any third party that makes a written alternative proposal that the JPE GP Board believes is bona fide so long as the JPE GP Board, after consultation with JPE GP’s outside legal counsel and financial advisors, determines in good faith that such alternative proposal constitutes or could reasonably be expected to lead to or result in a superior proposal and, after consultation with JPE GP’s outside legal counsel, that failure to furnish such information or participate in such discussions would be inconsistent with the JPE GP Board’s duties under the JPE partnership agreement or applicable law, and such alternative proposal did not result from a material breach of the no solicitation provisions in the Merger Agreement.

JPE has also agreed in the Merger Agreement that it (i) will promptly, and in any event within 48 hours after receipt, notify AMID of any alternative proposal or any request for information or inquiry with regard to any alternative proposal and the identity of the person making any such alternative proposal, request or inquiry (including providing AMID with copies of any written materials received from or on behalf of such person relating to such proposal, offer, request or inquiry) and (ii) will provide AMID with the material terms, conditions and nature of any such alternative proposal, request or inquiry. In addition, JPE agrees to keep AMID reasonably informed of all material developments affecting the status and terms of any such alternative proposals, offers, inquiries or requests (and promptly provide AMID with copies of any written materials received by it or that it has delivered to any third party making an alternative proposal that relate to such proposals, offers, requests or inquiries) and of the status of any such discussions or negotiations.

Change in JPE GP Board Recommendation (see page 92)

The Merger Agreement provides that JPE will not, and will cause its subsidiaries and use reasonable best efforts to cause its representatives not to, directly or indirectly, withdraw, modify or qualify, or propose publicly to withdraw, modify or qualify, in a manner adverse to AMID, the recommendation of the JPE GP Board that JPE’s Unitholders adopt the Merger Agreement or publicly recommend the approval or adoption of, or publicly approve or adopt, or propose to publicly recommend, approve or adopt, any alternative proposal. In addition, subject to certain limitations, if JPE receives an alternative proposal it will, within ten business days of receipt of a written request from AMID, publicly reconfirm the recommendation of the JPE GP Board that JPE’s Unitholders adopt the Merger Agreement.

JPE’s taking or failing to take, as applicable, any of the actions described above is referred to as an “adverse recommendation change.”

Subject to the satisfaction of specified conditions in the Merger Agreement described under “Proposal 1: The Merger Agreement—Change in JPE GP Board Recommendation,” the JPE GP Board may, at any time prior to the adoption of the Merger Agreement by JPE Unitholders, effect an adverse recommendation change in response to either (i) any alternative proposal constituting a superior proposal or (ii) a changed circumstance that was not known by the JPE GP Board prior to the date of the Merger Agreement, in each case if the JPE GP Board, after consultation with JPE GP’s outside legal counsel, determines in good faith that the failure to take such action would be inconsistent with its duties under the JPE partnership agreement or applicable law.

Termination of the Merger Agreement (see page 95)

AMID or JPE may terminate the Merger Agreement at any time prior to the Effective Time:

Termination Fee and Expense Reimbursement (see page 96)

Generally, all fees and expenses incurred in connection with the transactions contemplated by the Merger Agreement will be the obligation of the respective party incurring such fees and expenses.

In addition, following a termination of the Merger Agreement in specified circumstances, JPE will be required to pay all of the reasonably documented out-of-pocket expenses incurred by AMID and its controlled affiliates in connection with the Merger Agreement and the transactions contemplated thereby; provided, however, that in the event of a termination of the Merger Agreement by either party because the Merger Agreement was not adopted at the Special Meeting of JPE Unitholders called for such purpose (or termination by JPE pursuant to a different termination provision provided in the Merger Agreement at a time when the Merger Agreement is terminable because the Merger Agreement was not adopted at the Special Meeting of JPE Unitholders called for such purpose), JPE will pay AMID’s out-of-pocket expenses, in certain circumstances, up to a maximum amount of $5 million. Following payment of the termination fee, JPE will not be obligated to pay any additional expenses incurred by AMID or its affiliates.

Following termination of the Merger Agreement under specified circumstances, including due to an adverse recommendation change having occurred, JPE will be required to pay AMID a termination fee of $10 million, less any expenses previously reimbursed by JPE pursuant to the Merger Agreement. Following payment of the termination fee, JPE will not be obligated to pay any additional expenses incurred by AMID or its affiliates.

Comparison of Rights of AMID Unitholders and JPE Unitholders (see page 172)

JPE Unitholders will own AMID Common Units following the completion of the Merger, and their rights associated with those AMID Common Units will be governed by the AMID partnership agreement, which differs in a number of respects from the JPE partnership agreement, and the Delaware LP Act.

Material United States Federal Income Tax Consequences of the Merger (see page 117)

Tax matters associated with the Merger are complicated. The U.S. federal income tax consequences of the Merger to a holder of JPE Common Units or JPE Subordinated Units will depend, in part, on such unitholder’s own tax situation. The tax discussions contained herein focus on the U.S. federal income tax consequences generally applicable to individuals who are residents or citizens of the United States that hold their JPE Common Units or JPE Subordinated Units as capital assets, and these discussions have only limited application to other unitholders, including those subject to special tax treatment. Holders of JPE Common Units or JPE Subordinated Units are urged to consult their tax advisors for a full understanding of the U.S. federal, state, local and foreign tax consequences of the Merger that will be applicable to them.

In connection with the Merger, JPE expects to receive an opinion from Latham to the effect that (i) except to the extent that the Section 707 Consideration (as defined below) causes the transaction to be treated as a “disguised sale,” holders of JPE Common Units or JPE Subordinated Units (other than JPE Common Units or JPE Subordinated Units held by the Affiliated Unitholders and GP Sub) should not recognize any income or gain as a result of the Merger with respect to such JPE Common Units or JPE Subordinated Units held (other than any income or gain resulting from (a) the actual or constructive distribution of cash, including as a result of any decrease in partnership liabilities pursuant to Section 752 of the Code, or (b) the receipt of any non-pro rata merger consideration); provided that such opinion will not extend to any holder who acquired JPE Common Units or JPE Subordinated Units from JPE in exchange for property other than cash; and (ii) as of the closing date of the Merger, JPE is classified as a partnership for U.S. federal income tax purposes.

In connection with the Merger, AMID expects to receive an opinion from Locke Lord to the effect that (i) no AMID entity should recognize any income or gain as a result of the Merger (other than any gain resulting from any decrease in partnership liabilities pursuant to Section 752 of the Code); and (ii) no gain or loss should be recognized by holders of AMID Common Units as a result of the Merger with respect to such AMID Common Units held (other than any gain resulting from any decrease in partnership liabilities pursuant to Section 752 of the Code).

In connection with the Merger, AMID expects to receive an opinion from Holland & Hart, LLP to the effect that, as of the closing date of the Merger, AMID is classified as a partnership for U.S. federal income tax purposes.

Opinions of counsel, however, are subject to certain limitations and are not binding on the Internal Revenue Service (“IRS”) and no assurance can be given that the IRS would not successfully assert a contrary position regarding the Merger and the opinions of counsel. In addition, such opinions will be based upon certain factual assumptions and representations, warranties and covenants made by the officers of the AMID entities and JPE entities and any of their respective affiliates as to such matters as counsel may reasonably request. See “Material U.S. Federal Income Tax Consequences of the Merger” for a more complete discussion of the U.S. federal income tax consequences of the Merger.

Accounting Treatment of the Merger (see page 86)

AMID and JPE are under the common control of ArcLight. Despite the legal form of the transaction whereby AMID will be acquiring JPE, as ArcLight obtained control of JPE prior to obtaining control of AMID, JPE is considered to be acquiring AMID for financial reporting purposes and will account for the Merger as a

reorganization of entities under common control. As a result, JPE will record AMID’s historical financial statements after adjustments to reflect ArcLight’s related historical cost basis in AMID. JPE will also retrospectively adjust its historical financial statements to include the operating results of AMID beginning April 15, 2013, the date upon which common control began.

Listing of AMID Common Units; Delisting and Deregistration of JPE Common Units (see page 86)

AMID Common Units are currently listed on the NYSE under the ticker symbol “AMID.” It is a condition to closing that the AMID Common Units to be issued in the Merger to JPE Unitholders be approved for listing on the NYSE, subject to official notice of issuance.

JPE Common Units are currently listed on the NYSE under the ticker symbol “JPEP.” If the Merger is completed, JPE Common Units will cease to be listed on the NYSE and will be deregistered under the Exchange Act.

No Appraisal Rights (see page 86)

Appraisal rights are not available in connection with the Merger under the Delaware LP Act or under the JPE partnership agreement.

Organizational Structure Prior to and Following the Mergers

The following represents the simplified organizational structure of AMID and JPE prior to the Mergers⁽¹⁾:

The following represents the simplified organizational structure of the combined company following the Mergers⁽¹⁾:

Selected Historical Financial Information of AMID

The following table sets forth AMID’s selected historical consolidated financial and other data for the periods ended and as of the dates indicated. The consolidated statements of operations for the years ended December 31, 2013, 2014 and 2015 and the consolidated balance sheet data as of December 31, 2014 and 2015 have been derived from AMID’s audited consolidated financial statements incorporated by reference into this proxy statement/prospectus. The consolidated statements of operations for the years ended December 31, 2011 and 2012 and the consolidated balance sheet data as of December 31, 2011, 2012 and 2013 have been derived from AMID’s audited consolidated financial statements that are not incorporated by reference into this proxy statement/prospectus. The consolidated statements of operations for the nine months ended September 30, 2015 and 2016 and the consolidated balance sheet data as of September 30, 2016 have been derived from AMID’s unaudited condensed consolidated financial statements incorporated by reference into this proxy statement/prospectus. The consolidated balance sheet data as of September 30, 2015 has been derived from AMID’s unaudited condensed consolidated financial statements that are not incorporated by reference into this proxy statement/prospectus. The data presented below should be read in conjunction with the section entitled “Management’s Discussion and Analysis of Financial Condition and Results of Operations” and the consolidated financial statements and the related notes contained in AMID’s most recent Annual Report on Form 10-K and its Quarterly Report on Form 10-Q for the period ended September 30, 2016, incorporated by reference into this proxy statement/prospectus. See the section entitled “Where You Can Find More Information” beginning on page 203 of this proxy statement/prospectus.

Adjusted EBITDA

Adjusted EBITDA is a measure used by AMID’s management and by external users of AMID’s financial statements, such as investors, commercial banks, research analysts and others, to assess:

AMID defines Adjusted EBITDA as net income (loss) attributable to the partnership of AMID (the “Partnership”), plus interest expense, income tax expense, depreciation, amortization and accretion expense, certain non-cash charges such as non-cash equity compensation expense, unrealized (gains) losses on derivatives, debt issuance costs paid during the period, distributions from investments in unconsolidated affiliates, transaction expenses and selected charges that are unusual or nonrecurring, less, earnings in unconsolidated affiliates, gains (losses) on sale of assets, net and selected gains that are unusual or nonrecurring. The GAAP measure most directly comparable to Adjusted EBITDA is net income (loss) attributable to the Partnership. For a reconciliation of Adjusted EBITDA to net income (loss), please read “—Note About Non-GAAP Financial Measures.”

Segment gross margin for AMID’s gathering and processing segment is defined as total revenue generated from gathering and processing operations less unrealized gains or plus unrealized losses on commodity derivatives, less the cost of natural gas, crude oil, NGLs and condensate purchased and revenue from construction, operating and maintenance agreements (“COMA”).

Segment gross margin for AMID’s Transmission segment is defined as total revenue less COMA income and the cost of natural gas purchased in connection with fixed margin arrangements.

Segment gross margin for AMID’s Terminals segment is defined as total revenue less direct operating expense which includes direct labor, general materials and supplies and direct overhead.

Gross margin is a metric that AMID uses to evaluate its performance. AMID defines gross margin as the sum of its segment gross margin for its Gathering and Processing, Transmission and Terminals segments. The GAAP measure most directly comparable to gross margin is Net income (loss) attributable to the Partnership.

Note About Non-GAAP Financial Measures

Gross margin, segment gross margin and Adjusted EBITDA are performance measures that are considered non-GAAP financial measures. Each measure has important limitations as an analytical tool because it excludes some, but not all, items that affect the most directly comparable GAAP financial measure. AMID’s management compensates for the limitations of these non-GAAP measures as analytical tools by reviewing the comparable GAAP measures, understanding the differences between the measures and incorporating these data points into management’s decision-making process.

Investors should not consider gross margin, segment gross margin or Adjusted EBITDA in isolation or as a substitute for, or more meaningful than analysis of, AMID’s results as reported under GAAP. Gross margin, segment gross margin and Adjusted EBITDA may be defined differently by other companies in AMID’s industry.

The following tables reconcile the non-GAAP financial measures of gross margin and Adjusted EBITDA used by AMID’s management to net income (loss) attributable to the Partnership, their most directly comparable GAAP measure, for each of the years ended December 31, 2015, 2014, 2013, 2012, and 2011 (in thousands), and for the nine months ended September 30, 2016 and 2015 (in thousands):