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 387 I-10. After the interchange with I-10, the highway intersects SR 187, with SR 387 turning towards the east at the intersection. The highway continues to the east-northeast until it reaches its northern terminus at SR 87. The route was established between 1946 and 1951, from SR 187 to SR 87 just south of Sun Lakes. Between 1958 and 1961, it was cancelled, and became part of SR 93, a proposed extension of US 93. In 1967, SR 387 was designated from SR 93 to SR 87. It extended south over part of SR 93 on December 17, 1984. Arizona State