Lost Trail Pass is a mountain pass in the Rocky Mountains of the United States, on the border of Idaho and Montana in the Bitterroot Mountains. The pass is at an elevation of 7014 feet (2138 m) above sea level and is traversed by U.S. Highway 93. The pass is about a half-mile (1 km) west of the continental divide, which retreats eastward at this point, inside Montana along the Ravalli-Beaverhead county border, toward Butte. The Lost Trail Powder Mountain ski area is at the pass, immediately west of US-93.