Idaho State Highway 51 February 2015, some map products such as Google Maps still show SH-51's former overlay with American Legion Blvd. SH-51's northern terminus is in the city of Mountain Home in Elmore County. After turning south from Airbase Rd. and the intersection with SH-67, the road crosses the Snake River into Owyhee County and passes through the towns of Bruneau, Grasmere, and Riddle. About from the state border it enters the Duck Valley Indian Reservation. As the road crosses into Nevada it becomes State Route 225. The reservation's only major town, Owyhee is about south of the state border. After another through
U.S. Route 51 in Louisiana intersects LA 38, the main east–west thoroughfare, at Avenue G. The highway curves to the northeast on the way out of town and continues for another to the state line. During this stretch is the final junction with a state route, LA 1054, in an area known as Greenlaw. Immediately across the state line, US 51 continues into the Pike County, Mississippi town of Osyka en route to McComb. The portions of US 51 not concurrent with I-55 are generally classified as an urban or rural major collector by the Louisiana Department of Transportation and Development (La DOTD). However, the