U.S. Route 66 in Arizona U.S. Route 66 in Arizona U.S. Route 66 (US 66, Route 66) covered as part of a former United States Numbered Highway in the state of Arizona. The highway ran from west to east, starting in Needles, California, through Kingman and Seligman to the New Mexico state line as part of the historic US 66 from Santa Monica, California, to Chicago, Illinois. The highway was decommissioned in 1985, although portions remain as State Route 66 (SR 66). In 1914 the road was designated National Old Trails Highway; in 1926 it was re-designated US 66 with the birth of the U.S.
Arizona State Route 66 line, much of US 66 has been replaced with I-40. Various stretches of the old highway exist as frontage roads and business loops of I-40. In 1984, US 66 was officially removed from the state highway system of Arizona. Most of the old highway had been replaced by I-40, but the portion between Kingman and Seligman where I-40 followed a new alignment to the south became SR 66. In 1990, the state turned over the easternmost of SR 66 (known as Crookton Rd) to Yavapai County for maintenance. Arizona State Route 66 State Route 66 (SR 66) is a surface