Map of US highway 81 and family, and US 73
US 73 is represented by the purple line from Dawson NE to Kansas City. The red lines extending north and south of those points show the historic splits and extents of US 73.
US 81 is the purple line beginning in Pembina ND. Its southern terminus is currently near Fort Worth TX; the red line extending south of there to Laredo is the historic extent of US 81.
US 181 is the blue line from San Antonio to Corpus Christi TX.
US 281 is the blue line from Dunseith ND to Brownsville TX. Its historic routings are shown in red.
