Idaho State Highway 51

State Highway 51
Route information
Maintained by ITD
Length:	93.598 mi (150.631 km)
Major junctions
South end:	SR 225 near Owyhee, NV
	SH-78 SH-67
North end:	I-84 Business Loop at intersection with American Legion Blvd. in Mountain Home
Location
Counties:	Owyhee, Elmore
Highway system
State Highways in Idaho ← SH-50 SH-52 →

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 February 2015, some map products such as Google Maps still show SH-51's former overlay with American Legion Blvd.

Route description

View north from the south end of SH-51

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 11.5 miles (18.5 km) 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 4 miles (6.4 km) south of the state border. After another 95 miles (153 km) through Elko County, 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.

Major intersections and Points of Interest

County	Location	mi	km	Destinations	Notes
Owyhee	Duck Valley Indian Reservation	0.000	0.000	SR 225 south to I‑80 – Owyhee, Elko, Reno	Southern terminus of SH-51
		1.458	2.346	BIA Road 7
		2.925	4.707	BIA Road 8
		7.260	11.684	BIA Road 211
		11.415	18.371	Duck Valley Indian Reservation	Northern border of reservation
	​	26.410– 26.503	42.503– 42.652	Rest Area
	​	69.715– 69.916	112.195– 112.519	SH-78 west – Grand View, Marsing	Western end of SH-78 overlap
	Bruneau	76.186– 76.240	122.609– 122.696	Roadside Picnic Area
		76.582	123.247	SH-78 east – Bruneau Dunes State Park, Hammett	Eastern end of SH-78 overlap
	Snake River	76.979	123.886	Snake River bridge Owyhee–Elmore county Line
Elmore	Mountain Home	88.294	142.095	West 36th Street South	Old Grandview Road
		90.785	146.104	SH-67 west – Mountain Home AFB, Grand View
		91.948– 93.598	147.976– 150.631	I-84 Business Loop – Boise, Glenns Ferry, Twin Falls	Overlap on I-84 Bus. (old US-26/30) to official northern terminus at American Legion Blvd. (old US-20)
1.000 mi = 1.609 km; 1.000 km = 0.621 mi       Concurrency terminus

Elevation

Elevation 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 Nevada border.

Location	Milepost	Elevation	GNIS Feature ID	(GNIS search)
Mountain Home	92	3146' - 959 m	374044
C.J. Strike Reservoir (Snake River)	76.98	2461' - 750 m	398659
Bruneau	71.49	2549' - 777 m	396181
Grasmere	32.50	5089' - 1551 m	376052
Riddle	13.49	5367' - 1636 m	398043
Miller Creek Settlement	6.0	5325' - 1623 m	396897
Owyhee, Nevada	(0)	5400' - 1646 m	842663