Lolo Pass, elevation 5,233 feet (1,595 m), is a mountain pass in the western United States, in the Bitterroot Range of the northern Rocky Mountains. It is on the border between the states of Montana and Idaho, approximately 40 miles (64 km) west-southwest of Missoula, Montana.
The pass is the highest point of the historic Lolo Trail, between the Bitterroot Valley in Montana and the Weippe Prairie in Idaho. The trail, known as naptniĊĦaqs, or "Nez Perce Trail" in Salish, was used by Nez Perce in the 18th century, and by the Lewis and Clark Expedition, guided by Old Toby of the Shoshone, on their westward snowbound journey in September 1805. After a winter at Fort Clatsop in present-day northwestern Oregon, the Corps of Discovery returned the following June. The Lolo Trail is a National Historic Landmark.