1. Colorado-Gulf Highway proposed by the Colorado to Gulf Highway Association, also advocated by the National Highways Association, Washington, D.C., May 1922. [cartographic material] Yale Public content 1922. 2020-01-10T20:49:33Z. 2020-01-14T22:32:52Z. National Highways Association, author. National Highways Association. English. cartographic image. Public. United States and United States.