The highway has alternately (and unofficially) been known as part of the Pan-American Highway. The route of US 81 follows that of the old Meridian Highway (so called because it roughly followed the Sixth Principal Meridian of the US Public Land Survey System) which dates back as early as 1911.
highway that extends for 1,220 miles (1,960 km) in the central United States and is one of the original United States Numbered Highways established in 1926 by the American Association of State Highway Officials. Highway 81 ( US 81) is a major north–south U.S. Texas, Oklahoma, Kansas, Nebraska, South Dakota, North Dakota I-29 / PTH 75 at Pembina–Emerson Border Crossing near Pembina, ND
