U.S. Route 180 is an east–west United States highway. Like many three-digit routes, US 180 no longer meets its "parent", US 80. US 80 was decommissioned west of Mesquite, Texas, and was replaced in Texas by Interstate 20 and Interstate 10 resulting in U.S. 180 being 57 miles longer than U.S. 80. The highway's eastern terminus is in Hudson Oaks, Texas, at an intersection with Interstate 20. Its western terminus is unclear. Signage at an intersection with State Route 64 in Valle, Arizona 40 miles (64 km) northwest of Flagstaff indicates that the route starts at SR 64, which is consistent with the AASHTO U.S. Highway logs. However, many maps continue the US 180 designation to the south rim of the Grand Canyon at Grand Canyon Village. Signage at the SR 64 intersection as of 2021 indicated that US 180 continues north concurrent with the route. However, no signage along the route exists past this intersection until SR 64 turns east towards Cameron, Arizona. At this intersection, signage makes no mention of US 180 nor is there any mention at the terminus of SR 64 at US 89.

U.S. Route 80 or U.S. Highway 80 (US 80) is a major east–west United States Numbered Highway in the Southern United States, much of which was once part of the early auto trail known as the Dixie Overland Highway. As the "0" in the route number indicates, it was originally a cross-country route, from the Pacific Ocean to the Atlantic Ocean. Its original western terminus was at Historic US 101 in San Diego, California. However, the entire segment west of Dallas, Texas, has been decommissioned in favor of various Interstate Highways and state highways. Currently, the highway's western terminus is at an interchange with Interstate 30 (I-30) on the Dallas–Mesquite city line. Its eastern terminus is in Tybee Island, Georgia near the Atlantic Ocean. Between Jonesville, Texas and Kewanee, Mississippi, US 80 runs parallel to or concurrently with Interstate 20. It also currently runs through Dallas, Texas; Shreveport, Louisiana; Jackson, Mississippi; Montgomery, Alabama; Columbus, Georgia; Macon, Georgia; and Savannah, Georgia.