A proposed pipeline system to transport gas from the Prudhoe Bay field in Alaska to the vicinity of Chicago and San Francisco through Canada. Portions from Canada towards San Francisco (the Western Leg) and from Canada towards Chicago (Northern Border Pipeline) were "prebuilt" to import gas from Canada prior to the flow of Alaskan gas. The project was authorized by the ANGTA of 1976 and the President's Decision and Report to Congress in September 1977.