1985: Route 66 officially removed from U.S. Highway System

A grassy stretch of old 66 near Bard, New Mexico. (Six Gun Siding)

(Wikipedia) ... The beginning of the decline for US 66 came in 1956 with the signing of the Interstate Highway Act by President Dwight Eisenhower who was influenced by his experiences in 1919 as a young Army officer crossing the country in a truck convoy (following the route of the Lincoln Highway), and his appreciation of the German Autobahn network as a necessary component of a national defense system.
During its nearly 60-year existence, US 66 was under constant change. Continued