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
Utah State Route 51 Utah State Route 51 State Route 51 is a short highway completely within Utah County in northern Utah that connects SR-147 to US-89. The highway runs for three miles (5 km) and is an old routing of U.S. Route 91. The route begins at the intersection of 400 North (SR-147) and Childs Road in Spanish Fork, SR-51 heading northeast as a two-lane undivided highway on the latter. As the road exits Spanish Fork, it heads into a rural portion of Utah County. The continues northeast until 1600 North south of Springville, where the road turns north. The road continues north