U.S. Route 83 (US 83) is a major north–south United States Numbered Highway that extends 1,885 miles (3,034 km) in the central United States. Only four other north–south routes are longer: US 1, US 41, US 59, and US 87, while US 83 follows a straighter north-south path than all of these. Nearly half of its mileage is in the state of Texas. The highway's northern terminus is north of Westhope, North Dakota, at the Canadian border, where it continues as Manitoba Highway 83 (PTH 83). The southern terminus is at the Veterans International Bridge in Brownsville, Texas. Together, US 83 and PTH 83 form a continuously numbered north-south highway with a combined distance of 3,450 kilometres (2,140 mi).

U.S. Route 59 is a north–south United States highway. A latecomer to the U.S. numbered route system, US 59 is now a border-to-border route, part of the NAFTA Corridor Highway System. It parallels U.S. Route 75 for nearly its entire route, never much more than 100 miles (160 km) away, until it veers southwest in Houston, Texas. Its number is out of place since US 59 is either concurrent with or entirely west of U.S. Route 71. The highway's northern terminus is 9 mi (14 km) north of Lancaster, Minnesota, at the Lancaster–Tolstoi Border Crossing on the Canada–US border, where it continues as Manitoba Highway 59. Its southern terminus is at the Mexico–US border in Laredo, Texas, where it continues as Mexican Federal Highway 85D.