Idaho State Highway 51 Idaho State Highway 51 State Highway 51 (SH-51) is a state highway in southwestern Idaho from Mountain Home south to the Nevada border, where it continues as State Route 225 to Elko. It is the major north–south road in Owyhee County. As currently configured in the state's official milepoint log, SH-51 terminates at the BL-84 intersection with American Legion Blvd., and is not otherwise officially concurrent/overlaid with BL-84 (where the signs at I-84's Exits 90 and 99 say "To SH-51/To SH-67") or the former section of US-20 that follows American Legion Blvd. to I-84/US-20 east at Exit 95. As of
Oklahoma State Highway 51 Oklahoma State Highway 51 State Highway 51, abbreviated to SH-51 or OK-51, is a major state highway in Oklahoma. It runs for 333 miles (535½ km) east–west across the state, running from the Texas state line to Arkansas. It is the third-longest state highway in the system. SH-51 begins at the Texas line concurrent with US-60 just east of Higgins, Texas. It remains concurrent for 61 miles (98 km) until it reaches US-270/US-281/SH-3 at Seiling, Oklahoma. At Seiling, SH-51 joins with those three highways for nine miles (14 km) before splitting off on its own. 11 miles (18 km) after