State Route 140 begins at a junction with
U.S. Route 95 about north of
Winnemucca in the Quinn River Valley. From this point, the highway heads west towards the sparsely populated regions of northwestern Nevada. SR 140 crosses into the
Desert Valley before entering a branch of the
Fort McDermitt Indian Reservation. Inside the reservation, the route crosses the
Quinn River. Upon exiting the Indian territory, SR 140 curves northwest to parallel the Quinn River for about as it rounds the northern edge of the
Jackson Mountains. As the river turns southeast towards the
Black Rock Desert, the highway continues its northwest trajectory through the valley between the
Bilk Creek Mountains on the east and the
Pine Forest Range to the west. The route crosses over the Denio Summit before reaching
Denio Junction.
State Route 292 intersects the highway here, providing access to
Denio, the only town in this region of Nevada. At Denio Junction, State Route 140 turns westward past the south end of the
Pueblo Mountains. About from the junction, the highway enters Virgin Creek Valley. Near this valley, SR 140 enters the
Sheldon National Wildlife Refuge, an area designed to provide habitat for
pronghorn and conserve native fish, bird and plant species. The highway travels about through the wildlife range towards the Oregon state line. SR 140 ends at the border in the northwest corner of Humboldt County, with
Oregon Route 140 continuing northwest towards
Adel and
Lakeview. ==History==