Sand Mountain is a Singing sand dune 20 miles (32 km) east of Fallon, Nevada along U.S. Route 50. The dune is two miles long and 600 feet (180 m) high. It lies on the edge of the ancient Lake Lahontan, that for the most part dried up 9,000 years ago. Sand Mountain Recreation Area is managed by the Bureau of Land Management and is open to off-highway vehicle use. The area is also the only home of the Sand Mountain Blue Butterfly.