State Highway 51 (SH-51) is a state highway in southwestern

Idaho Idaho ( ) is a state in the Pacific Northwest region of the Western United States. To the north, it shares a small portion of the Canada–United States border with the province of British Columbia. It borders the states of Montana and Wyomi ...

from Mountain Home south to the

Nevada Nevada ( ; ) is a state in the Western region of the United States. It is bordered by Oregon to the northwest, Idaho to the northeast, California to the west, Arizona to the southeast, and Utah to the east. Nevada is the 7th-most extensive, ...

border, where it continues as State Route 225 to Elko. It is the major north–south road in

Owyhee County Owyhee County ( ) is a county in the southwestern corner of the U.S. state of Idaho. As of the 2020 census, the population was 12,133. The county seat is Murphy, and its largest city is Homedale. In area it is the second-largest county in Ida ...

. As currently configured in the state's official milepoint log, SH-51 terminates at the Business Loop 84 intersection with American Legion Boulevard, and is not otherwise officially concurrent/overlaid with BL-84 (where the signs at I-84's Exits 90 and 95 say "To SH-51/To SH-67") or the former section of US-20 that follows American Legion Boulevard to Interstate 84/U.S. Route 20 east at Exit 95. As of February 2015, some map products such as Google Maps still show SH-51's former overlay with American Legion Boulevard.

Route description

2014-08-19 14 38 45 First reassurance sign and mileage distance sign along northbound Idaho State Highway 51

SH-51's northern

terminus Terminus may refer to: * Bus terminus, a bus station serving as an end destination * Terminal train station or terminus, a railway station serving as an end destination Geography *Terminus, the unofficial original name of Atlanta, Georgia, United ...

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

and passes through the towns of Bruneau, Grasmere, and

Riddle A riddle is a statement, question or phrase having a double or veiled meaning, put forth as a puzzle to be solved. Riddles are of two types: ''enigmas'', which are problems generally expressed in metaphorical or allegorical language that requ ...

. About from the state border it enters the

Duck Valley Indian Reservation The Duck Valley Indian Reservation () was established in the 19th century for the federally recognized Shoshone- Paiute Tribe. It is isolated in the high desert of the western United States, and lies on the state line, the 42nd parallel, betwee ...

. As the road crosses into

it becomes State Route 225. The reservation's only major town, Owyhee is about south of the state border. After another through

Elko County Elko County is a county in the northeastern corner of Nevada, United States. As of the 2020 census, the population was 53,702. Its county seat is Elko. The county was established on March 5, 1869, from Lander County. Elko County is the fourth ...

, SR 225 connects with Interstate 80 in Elko.

History

The basic route of today's SH-51 was in place as early as the 1930s, mostly as an all-weather gravel road from Mountain Home until it reached the northern boundary of the Duck Valley Indian Reservation, and as an unimproved road on through to the Nevada border and then-NV Route 11 as of the 1937 map. Rand McNally and Company
Road map: Idaho, Mont., Wyo.
published by

Texaco Texaco, Inc. ("The Texas Company") is an American oil brand owned and operated by Chevron Corporation. Its flagship product is its fuel "Texaco with Techron". It also owned the Havoline motor oil brand. Texaco was an independent company unt ...

, 1937

Major intersections

Elevation

Elevation The elevation of a geographic location is its height above or below a fixed reference point, most commonly a reference geoid, a mathematical model of the Earth's sea level as an equipotential gravitational surface (see Geodetic datum § Ver ...

on the highway ranges from a low of 2461 feet (750 m) above sea level at the Snake River crossing,
to a high of 5400 feet (1646 m) at the

border.

References

{{commons category, Idaho State Highway 51 051 Transportation in Owyhee County, Idaho Transportation in Elmore County, Idaho