THIRTEENTH SUPPLEMENTAL INDENTURE

Exhibit 4

EL PASO CORPORATION

as Issuer

and

HSBC BANK USA, NATIONAL ASSOCIATION

as Trustee

THIRTEENTH SUPPLEMENTAL INDENTURE

Dated as of May 30, 2008

to

INDENTURE

Dated as of May 10, 1999

$600,000,000 7.25% Senior Notes due 2018

TABLE OF CONTENTS

      THIRTEENTH SUPPLEMENTAL INDENTURE , dated as of May 30, 2008 (this “ Supplemental Indenture ”), between EL PASO CORPORATION , a Delaware corporation (the “ Company ”), and HSBC BANK USA, NATIONAL ASSOCIATION , a national banking association, as successor-in-interest to JPMorgan Chase Bank (formerly The Chase Manhattan Bank), as trustee under the Indenture referred to below (in such capacity, the “ Trustee ”).

RECITALS OF THE COMPANY

     WHEREAS, the Company and the Trustee are parties to an Indenture dated as of May 10, 1999 (as amended and supplemented from time to time, the “ Indenture ”), providing for the issuance from time to time of one or more series of the Company’s unsecured debentures, notes or other evidences of indebtedness (the “ Securities ”), the terms of which are to be determined as set forth in Section 301 of the Indenture; and

     WHEREAS, pursuant to Section 901 of the Indenture, without the consent of any Holders, the Company and the Trustee, at any time and from time to time, may enter into one or more indentures supplemental to the Indenture to establish the form or terms of securities of any series as permitted by Sections 201 and 301 of the Indenture; and

     WHEREAS, pursuant to this Supplemental Indenture, the Company desires to create a new series of Securities under the Indenture, to be titled the 7.25% Senior Notes due 2018 in an initial aggregate principal amount of $600,000,000 (the “ Notes ”) and to establish the forms and the terms and conditions thereof;

     WHEREAS, all action on the part of the Company necessary to authorize the issuance of the Notes under the Indenture and this Supplemental Indenture has been duly taken; and

     WHEREAS, all acts and things necessary to make the Notes, when executed by the Company and authenticated and delivered by the Trustee as provided in the Indenture and this Supplemental Indenture, the valid and binding obligations of the Company and to make this Supplemental Indenture a valid and binding agreement in accordance with the Indenture have been done and performed;

     NOW, THEREFORE, in consideration of the premises, agreements and obligations set forth herein and for other good and valuable consideration, the receipt and sufficiency of which are hereby acknowledged, the parties hereto hereby agree, for the equal and proportionate benefit of all Holders of the Notes, as follows:

ARTICLE 1
Relation to Indenture; Definitions

     Section 1.01 . Relation to Indenture. With respect to the Notes, this Supplemental Indenture constitutes an integral part of the Indenture.

     Section 1.02 . Definitions. For all purposes of this Supplemental Indenture, except as otherwise expressly provided herein, capitalized terms used herein and not otherwise defined herein shall have the meanings assigned thereto in the Indenture.

     Section 1.03 . General References. All references in this Supplemental Indenture to Articles and Sections, unless otherwise specified, refer to the corresponding Articles and Sections of this Supplemental Indenture; and the terms “ herein ”, “ hereof” , “ hereunder ” and any other word of similar import refers to this Supplemental Indenture.

ARTICLE 2
Terms and Issuance

     Section 2.01. Issue of Notes . A new series of Securities is to be issued under the Indenture as supplemented by this Supplemental Indenture. The series shall be titled the “7.25% Senior Notes due 2018.”

     Section 2.02. Form of Notes, Authentication Certificate . The new series of Notes initially shall be issuable in the form of one or more Global Securities, registered in the name of the Depositary or its nominee. The Depository Trust Company shall be the Depositary for such Global Securities. The form and terms of the Notes and the Trustee’s certificate of authentication shall be substantially as set forth in Exhibit A hereto. Except as otherwise provided herein, the Notes shall in all respects be subject to the terms, conditions and covenants of the Indenture as supplemented by this Supplemental Indenture (including the applicable form of Note set forth as Exhibit A hereto (the terms of which are incorporated in and made a part of this Supplemental Indenture for all intents and purposes)). In the event of any inconsistency between the provisions of this Supplemental Indenture and the provisions of the Indenture, the provisions of this Supplemental Indenture shall be controlling with respect to the Notes.

     Section 2.03. Additional Notes . The Company will initially issue $600,000,000 aggregate principal amount of the Notes. The Notes may be reopened, without the consent of the Holders thereof, for increases in the aggregate principal amount of the Notes and issuance of additional Notes. Any additional Notes shall be consolidated and form a single series with, and shall have the same terms as to status, redemption or otherwise as the Notes then outstanding, except for issue date, issue price and, if applicable, first interest

payment date. No additional Notes may be issued if an Event of Default under the Indenture has occurred and is continuing with respect to the Notes.

ARTICLE 3
Miscellaneous

     Section 3.01 . Certain Trustee Matters. The recitals contained herein shall be taken as the statements of the Company, and the Trustee assumes no responsibility for their correctness. The Trustee makes no representations as to the validity or sufficiency of this Supplemental Indenture or the Notes or the proper authorization or the due execution hereof or thereof by the Company.

     Section 3.02 . Continued Effect. Except as expressly supplemented and amended by this Supplemental Indenture, the Indenture shall continue in full force and effect in accordance with the provisions thereof, and the Indenture (as further supplemented and amended by this Supplemental Indenture) is in all respects hereby ratified and confirmed. This Supplemental Indenture and all its provisions shall be deemed a part of the Indenture in the manner and to the extent herein and therein provided.

     Section 3.03 . Provisions Binding on Company’s Successors. All the covenants, stipulations, promises and agreements in this Supplemental Indenture contained by the Company shall bind its successors and assigns whether so expressed or not.

     Section 3.04 . Governing Law. THIS SUPPLEMENTAL INDENTURE AND THE NOTES SHALL BE GOVERNED BY AND CONSTRUED IN ACCORDANCE WITH THE LAWS OF THE STATE OF NEW YORK.

     Section 3.05 . Counterparts. This instrument may be executed in any number of counterparts, each of which shall be deemed to be an original, but all such counterparts shall together constitute but one and the same instrument.

(Signature Pages Follow)

     IN WITNESS WHEREOF, the parties hereto have caused this Supplemental Indenture to be duly executed and delivered, all as of the day and year first above written.

[Signature Page of Thirteenth Supplemental Indenture]

EXHIBIT A

     [THIS SECURITY IS A GLOBAL SECURITY WITHIN THE MEANING OF THE INDENTURE HEREINAFTER REFERRED TO AND IS REGISTERED IN THE NAME OF A DEPOSITARY OR A NOMINEE THEREOF. THIS SECURITY MAY NOT BE TRANSFERRED TO, OR REGISTERED OR EXCHANGED FOR SECURITIES REGISTERED IN THE NAME OF, ANY PERSON OTHER THAN THE DEPOSITARY OR A NOMINEE THEREOF AND NO SUCH TRANSFER MAY BE REGISTERED, EXCEPT IN THE LIMITED CIRCUMSTANCES DESCRIBED IN THE INDENTURE. EVERY SECURITY AUTHENTICATED AND DELIVERED UPON REGISTRATION OF, TRANSFER OF, OR IN EXCHANGE FOR OR IN LIEU OF, THIS SECURITY SHALL BE A GLOBAL SECURITY SUBJECT TO THE FOREGOING, EXCEPT IN SUCH LIMITED CIRCUMSTANCES.

     UNLESS THIS SECURITY IS PRESENTED BY AN AUTHORIZED REPRESENTATIVE OF THE DEPOSITORY TRUST COMPANY, A NEW YORK CORPORATION, TO THE COMPANY OR ITS AGENT FOR REGISTRATION OF TRANSFER, EXCHANGE OR PAYMENT, AND ANY SECURITY ISSUED IS REGISTERED IN THE NAME OF CEDE & CO. OR SUCH OTHER NAME AS IS REQUESTED BY AN AUTHORIZED REPRESENTATIVE OF THE DEPOSITORY TRUST COMPANY (AND ANY PAYMENT IS MADE TO CEDE & CO. OR TO SUCH OTHER ENTITY AS IS REQUESTED BY AN AUTHORIZED REPRESENTATIVE OF THE DEPOSITORY TRUST COMPANY), ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO ANY PERSON IS WRONGFUL SINCE THE REGISTERED OWNER HEREOF, CEDE & CO., HAS AN INTEREST HEREIN.] ¹

EL PASO CORPORATION

7.25% SENIOR NOTE DUE 2018

CUSIP NO. 28336L BR9

     EL PASO CORPORATION, a corporation duly incorporated and existing under the laws of Delaware (herein called the “ Company ”, which term includes any successor Person under the Indenture hereinafter referred to), for value received, hereby promises to pay to [CEDE & Co.] ² , or registered assigns, the principal sum of                      United States Dollars on June 1, 2018 and to pay

interest thereon from May 30, 2008, or from the most recent Interest Payment Date to which interest has been paid or duly provided for, semi-annually in arrears on June 1 and December 1 of each year, commencing December 1, 2008, at the rate of 7.25% per annum, until the principal hereof is paid or made available for payment. The interest so payable, and punctually paid or duly provided for, on any Interest Payment Date will, as provided in such Indenture, be paid to the Person in whose name this Security (or one or more Predecessor Securities) is registered at the close of business on the Regular Record Date for such interest, which shall be the May 15 or November 15 (whether or not a Business Day), as the case may be, next preceding such Interest Payment Date. Any such interest not so punctually paid or duly provided for will forthwith cease to be payable to the Holder on such Regular Record Date and may either be paid to the Person in whose name this Security (or one or more Predecessor Securities) is registered at the close of business on a Special Record Date for the payment of such Defaulted Interest to be fixed by the Trustee, notice of which shall be given to Holders of Securities of this series not less than 10 days prior to such Special Record Date, or be paid at any time in any other lawful manner not inconsistent with the requirements of any securities exchange on which the Securities of this series may be listed, and upon such notice as may be required by such exchange, all as more fully provided in such Indenture. Interest will be payable on overdue interest to the extent permitted by law at the same rate as interest is payable on principal.

     [Payment of the principal of (and premium, if any) and interest on this Security will be made by transfer of immediately available funds to a bank account in New York, New York designated by the Holder in such coin or currency of the United States of America as at the time of payment is legal tender for payment of public and private debts.] ³

     [Payment of the principal of (and premium, if any) and interest on this Security will be made at the office or agency of the Company maintained for that purpose in the Borough of Manhattan, The City of New York, in such coin or currency of the United States of America as at the time of payment is legal tender for payment of public and private debts; provided, however, that payment of interest may be made at the option of the Company by check mailed to the addresses of the Persons entitled thereto as such addresses shall appear in the Security
Register.] ⁴

     Reference is hereby made to the further provisions of this Security set forth on the reverse hereof, which further provisions shall for all purposes have the same effect as if set forth at this place.

     Unless the certificate of authentication hereon has been executed by the Trustee referred to on the reverse hereof by manual signature, this Security shall not be entitled to any benefit under the Indenture or be valid or obligatory for any purpose.

     IN WITNESS WHEREOF, the Company has caused this instrument to be duly executed.

     This is one of the Securities of the series designated therein referred to in the within-mentioned Indenture.

[REVERSE OF SECURITY]

El Paso Corporation
7.25% Senior Note due 2018

     This Security is one of a d