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 79 agency, as of 2011 Arizona State Route 79 was the fastest road in the nation, with the fastest 5% of the vehicles using it clocked at an average speed of 88 miles per hour. SR 79 is the section of what was together U.S. Route 80 and U.S. Route 89. US 80 was removed from Arizona in 1989, and US 89 was removed from southern Arizona in 1992. The original SR 79 was designated in 1924 as part of the original state highways from Prescott to Jerome. By 1926, it extended northeast to Flagstaff. In 1941, this was redesignated as