High Quality Content by WIKIPEDIA articles! U.S. Route 366 or US 366 was the designation of two child routes of the former U.S. Route 66 in New Mexico and Texas during the late 1920s and 1930s. Both alignments of US 366 were original U.S. Routes created in 1927. The first alignment was a route from El Paso, Texas to Amarillo, Texas crossing through New Mexico that existed until 1932. The second was a route from Albuquerque, New Mexico to Willard, New Mexico that was previously assigned a different route number before 1932. That alignment was canceled in the late 1930s.