The Mullan Pass is a mountain pass in the Rocky Mountains of Montana in the United States. It sits on the continental divide on the border between Powell County, Montana and Lewis and Clark County, Montana, 13.25 miles (21.32 km) west of Helena, Montana in Helena National Forest at a height of 5,902 feet (1,799 m).
The Northern Pacific Railway used the pass for its line from Logan, Montana to Garrison, Montana via Helena built in 1883. The line was the NP’s primary freight route, and was also used by their secondary passenger train, the Mainstreeter. The NP also built a line over Homestake Pass, which was used by their primary passenger train, the North Coast Limited. The rail line over Mullan Pass is currently operated by Montana RailLink.
The line crosses under the pass and continental divide at an elevation of 5,566 feet (1,697 m) via the 3,426-foot (1,044 m) long Mullan Tunnel. The pass was named after Lieutenant John Mullan, the army engineer who first crossed the pass on March 22, 1854 and later supervised construction of Mullan Road, the first road over the pass, in 1860.
Notable events :
On February 2, 1989, the Helena Train Wreck occurred when, during a significant cold snap, a train crew uncoupled the locomotives from a 48-car train due to mechanical issues. The air brakes failed on the cars, and the train rolled nine miles back into Helena, Montana where at approximately 5:30 am, they collided with a parked work train and caught fire. An explosion later linked to a tanker car filled with hydrogen peroxide shook the town, knocked out power, and caused extensive damage in the community, but no deaths.