REGISTRATION RIGHTS AGREEMENT

     THIS REGISTRATION RIGHTS AGREEMENT (the Agreement) is made and entered into as of April 5, 2007, among Northwest Pipeline Corporation (the Company), a corporation duly organized and existing under the laws of the State of Delaware, and Greenwich Capital Markets, Inc. and Banc of America Securities LLC, acting on behalf of themselves and the several initial purchasers listed on Schedule I hereto (the Initial Purchasers).

     This Agreement is made pursuant to the Purchase Agreement dated as of April 2, 2007, among the Company and Greenwich Capital Markets, Inc. and Banc of America Securities LLC, as representatives of the Initial Purchasers (the Purchase Agreement), which provides for the sale by the Company to the Initial Purchasers of $185,000,000 principal amount of its 5.95% Senior Notes due 2017 (the Securities). The Securities are to be issued pursuant to the provisions of an Indenture dated the date hereof (as amended, supplemented or otherwise modified from time to time, the Indenture) by and among the Company and The Bank of New York, as trustee (the Trustee).

     In order to induce the Initial Purchasers to enter into the Purchase Agreement, the Company has agreed to provide to each Initial Purchaser and its direct and indirect transferees the registration rights with respect to the Securities set forth in this Agreement. The execution of this Agreement is a condition to the closing under the Purchase Agreement.

     In consideration of the foregoing, the parties hereto agree as follows:

     1. Definitions.

     As used in this Agreement, the following capitalized defined terms have the following meanings:

     1933 Act shall mean the Securities Act of 1933, as amended from time to time.

     1934 Act shall mean the Securities Exchange Act of 1934, as amended from time to time.

     Additional Interest shall have the meaning set forth in Section 2(e).

     Agreement shall have the meaning set forth in the preamble.

     Business Day shall have the meaning set forth in Rule 13e-4(a)(3) under the 1934 Act.

     Closing Date shall mean the Closing Date as defined in the Purchase Agreement.

     Commission shall mean the Securities and Exchange Commission.

     Company shall have the meaning set forth in the preamble and also includes the Companys successors.

     Exchange Dates shall have the meaning set forth in Section 2(a)(ii).

     Exchange Offer Registration shall mean a registration under the 1933 Act effected pursuant to Section 2(a) hereof.

     Exchange Offer Registration Statement shall mean a registration statement on Form S-4 (or, if applicable, on another appropriate form) relating to an offering of Exchange Securities pursuant to an Registered Exchange Offer and all amendments and supplements to such registration statement, in each case including the Prospectus contained therein, all exhibits thereto and all material incorporated by reference therein.

     Exchange Securities shall mean any securities issued by the Company to be offered to Holders in exchange for Securities (pursuant to the Registered Exchange Offer or otherwise) pursuant to an Exchange Offer Registration Statement containing terms identical to the Securities for which they are exchanged except that (i) interest thereon shall accrue from the last date on which interest was paid on the Securities or, if no such interest has been paid, from the date of issuance of the Securities, and (ii) the Exchange Securities will not contain the legend appearing on the face of the Securities in the form recited in the Indenture and will not contain terms with respect to transfer restrictions.

     Holder shall mean each Initial Purchaser, for so long as it owns any Transfer Restricted Securities, and each of its successors, assigns and direct and indirect transferees who become registered owners of Transfer Restricted Securities under the Indenture; provided that for purposes of Sections 4 and 5 of this Agreement, the term Holder shall include Participating Broker-Dealers (as defined in Section 4(a)).

     Indemnified Party shall have the meaning set forth in Section 5(c).

     Indemnifying Party shall have the meaning set forth in Section 5(c).

     Indenture shall have the meaning set forth in the preamble.

     Initial Purchasers shall have the meaning set forth in the preamble.

     Majority Holders shall mean the Holders of a majority of the aggregate principal amount of outstanding Transfer Restricted Securities; provided that, for purposes of Section 6(b), whenever the consent or approval of Holders of a specified percentage of Transfer Restricted Securities is required hereunder, Transfer Restricted Securities held by the Company or any of its affiliates (as such term is defined in Rule 405 under the 1933 Act) (other than the Initial Purchasers or subsequent Holders of Transfer Restricted Securities if such subsequent Holders are deemed to be such affiliates solely by reason of their holding of such Transfer Restricted Securities) shall not be considered outstanding and shall not be counted in determining whether such consent or approval was given by the Holders of such required percentage or amount.