Idaho State Highway 51
SH-51 highlighted in red
|Maintained by ITD|
|Length||93.598 mi (150.631 km)|
|South end||SR 225 near Owyhee, NV|
| SH 78|
SH 67 near Mountain Home
|North end||I-84 Business Loop in Mountain Home|
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.
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.
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.
|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|
|SH 78 west – Grand View, Marsing||Western end of SH-78 overlap|
|||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|
|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|
|Location||Milepost||Elevation||GNIS Feature ID||(GNIS search)|
|Mountain Home||92||3146' - 959 m||374044|
|C.J. Strike Reservoir
|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|
- ITD (March 19, 2014). "State Highway 51 Milepoint Log" (PDF). Idaho Transportation Department. Retrieved February 5, 2015.
- Conley, Cort (1982). Idaho for the curious: a guide. Cambridge, Idaho: Backeddy Books. p. 281. ISBN 0-9603566-3-0.
- Rand McNally and Company, Road map: Idaho, Mont., Wyo., published by Texaco, 1937
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