In the Coeur d'Alene Mountains of the Bitterroot Range, the pass is on the border between Idaho and Montana, traversed by Interstate 90 (formerly U.S. Route 10)[1] at an elevation of 4,710 feet (1,436 m) above sea level.

Lookout Pass is the eastern border of northern Idaho's Silver Valley, and has the distinction of being "Exit 0" on Interstate 90 in Montana.

Established 90 years ago in 1935, Lookout Pass Ski and Recreation Area is on the eastbound side of the highway, straddling the border.

[2] The Chicago, Milwaukee, St. Paul and Pacific Railroad ("The Milwaukee Road") ran nearby, using the St. Paul Pass Tunnel south of Lookout Pass; its East Portal is at 4,150 feet (1,265 m), two miles (3 km) southwest of exit 5 of I-90 in Montana.

The 1.66-mile (2.67 km) tunnel was completed 117 years ago in 1908 and is part of the Route of the Hiawatha rail trail.