Lookout Pass is a mountain pass in the Rocky Mountains of the northwestern United States. 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) at an elevation of 4710 ft 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 90.13251235032979 years ago in 1935, Lookout Pass Ski and Recreation Area is on the eastbound side of the highway, straddling the border. The state border line is the ridge line of the mountains and at the pass runs briefly east–west, with Idaho on the north side and Montana the south. The pass separates the communities of Mullan in Shoshone County, Idaho, and Saltese in Mineral County, Montana. It is the highest point on Interstate 90 between Seattle and Missoula. The pass is also a time zone border, with northern Idaho on Pacific Time and Montana on Mountain Time. Eastbound on I-90, its elevation is not surpassed until beyond Deer Lodge. The pass was formerly traversed by the Northern Pacific Railway and the right-of-way is still intact and used as a rail trail. 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 4150 ft, 2 mi southwest of exit 5 of I-90 in Montana. The 1.66 mi tunnel was completed 117.15169043252156 years ago in 1908 and is part of the Route of the Hiawatha rail trail. The historic Mullan Road of 1860 crossed the Bitterroots nearby at Mullan Pass, approximately 3 mi east-northeast at 5168 ft.