Interstate 10 in Arizona 2013. The remainder of the old US 80 section was rebuilt to interstate standards, with completion in 2014. East of Tucson, I‑10 parallels and in some cases overlies old US 80 to Benson, and was originally co-signed as US 80 and SR 86. The section of I-10 from Valencia Road to Rita Road was the first construction project in the state of Arizona funded by the Federal Aid Highway Act of 1956. Construction began in 1957 and was completed in 1960. From Benson, the Interstate follows the Southern Pacific mainline east through Willcox and Bowie to New Mexico, rather than
Arizona State Route 66 Arizona State Route 66 State Route 66 (SR 66) is a surface road in the U.S. state of Arizona in Mohave and Coconino Counties. In 1914, the road was designated "National Old Trails Highway" but in 1926 was re-designated as U.S. Route 66. In 1985, U.S. Route 66 was dropped from the highway system. Parts of the highway were either absorbed into I-40, turned over to the state (SR 66), or turned over to Yavapai County. State Route 66 is a relic of the former U.S. Route 66 in Arizona and is the only part of old US 66 in