The tunnel was originally constructed for the Chicago, Milwaukee, St. Paul and Pacific Railroad in the early 1910s and was abandoned in 1980.

It replaced a temporary surface line over Snoqualmie Pass at 3,020 feet (920 m); this grade from Hyak to Rockdale later became U.S. Route 10, now the eastbound lanes of I-90.

In 1980, the Milwaukee Road received approval from the Interstate Commerce Commission to abandon its lines west of eastern Montana.

Today the tunnel is part of the Iron Horse State Park rails-to-trails project.

The $700,000 renovation added a four-inch (10 cm) layer of concrete to the walls and ceiling, a reinforced structure, and a new and improved walking surface of crushed rock.