Lanfair Valley is located in the Mojave Desert in southeastern California near the Nevada state line.

It passes eastwards just south of center at the Piute Range, and then through a central-southern stretch of the Piute Valley to its eastern terminus at Bullhead City Park, west bank of the Colorado River opposite Bullhead City, Arizona.

The Castle Mountains National Monument is part of the north and northeast perimeter of Lanfair Valley, (its watershed).

Tens of thousand of acres in the valley are privately held, despite being located in the Mojave National Preserve.

Few people live in the valley today, but at one time there were schools, farms, post offices, and even a railroad.