State Route 80 (SR 80) is a roughly arc-shaped highway lying in southeastern Arizona that, with New Mexico's State Road 80, is a relic of the old U.S. Route 80, now truncated from San Diego to Dallas. This segment of old US 80 was not closely paralleled by Interstate 10, which lies to its north and instead supplants the old and more direct (defunct in eastern Arizona) State Route 86.