U.S. Route 6 (US 6) or U.S. Highway 6 (US 6), also called the Grand Army of the Republic Highway, honoring the American Civil War veterans association, is a main route of the United States Numbered Highway System. While it currently runs east-northeast from Bishop, California, to Provincetown, Massachusetts, the route has been modified several times. The highway's longest-lasting routing, from 1936 to 1964, had its western terminus at Long Beach, California. During this time, US 6 was the longest highway in the country.

The White Mountains of California and Nevada are a triangular fault-block mountain range facing the Sierra Nevada across the upper Owens Valley. They extend for approximately 60 mi (97 km) as a greatly elevated plateau about 20 mi (32 km) wide on the south, narrowing to a point at the north, with elevations generally increasing south to north. The range's broad southern end is near the community of Big Pine, where Westgard Pass and Deep Springs Valley separate it from the Inyo Mountains. The narrow northern end is at Montgomery Pass, where U.S. Route 6 crosses. The Fish Lake Valley lies east of the range; the southeast part of the mountains are separated from the Silver Peak Range by block faulting across the Furnace Creek Fault Zone, forming a feeder valley to Fish Lake Valley. The range lies within the eastern section of the Inyo National Forest.