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                                                                     EXHIBIT 5.1

                    [FULBRIGHT & JAWORSKI L.L.P. LETTERHEAD]



May 16, 2001



Lakehead Pipe Line Company, Inc.
Lake Superior Place
21 West Superior Street
Duluth, Minnesota 55802

Gentlemen:

         We have acted as counsel to Lakehead Pipe Line Partners, L.P., a
Delaware limited partnership (the "Partnership"), and Lakehead Pipe Line
Company, Inc., a Delaware corporation and the general partner of the
Partnership, in connection with the offering and sale of $14,699,997 of
Class A Common Units (the "Units") pursuant to a Registration Statement filed
under Rule 462(b) of the General Rules and Regulations under the Securities Act
of 1933 (the "Registration Statement").

         As the basis for the opinion hereinafter expressed, we have examined
such statutes, regulations, corporate records and documents, certificates of
corporate and public officials, and other instruments as we have deemed
necessary or advisable for the purposes of this opinion. In such examination we
have assumed the authenticity of all documents submitted to us as originals and
for the conformity with the original documents of all documents submitted to us
as copies. Based on the foregoing and on such legal consideration as we deem
relevant, we are of the opinion that:

         1. The Partnership has been duly formed and is an existing
            limited partnership under the Delaware Revised Uniform
            Limited Partnership Act.

         2. The Units will, when issued and paid for as described in the
            Registration Statement, be duly authorized, validly issued, fully
            paid and nonassessable, except as such nonassessability may be
            affected by the matters described in the Partnership's Form 8-A, as
            amended, under the caption "Item 1. Description of Registrant's
            Securities to be Registered," which is incorporated by reference in
            the Prospectus included in the Registration Statement.

         We hereby consent to the filing of this opinion as an exhibit to the
Registration Statement and to the reference to us in the Registration Statement.

                              Very truly yours,

                              /s/ FULBRIGHT & JAWORSKI L.L.P.

                              Fulbright & Jaworski L.L.P.