The St. Paul Pass Tunnel

One of the Milwaukee Road's most famous tunnels along its Pacific Coast Extension was located in the Bitterroot Mountains at St. Paul Pass along the border of Idaho and Montana. One of the tougher sections of the route to survey and build due to its remoteness it took crews nearly two years to lay out all possible routes before engineers and the railroad eventually chose the route over the pass and begin construction. The tunnel, nearly a mile high in elevation and over a mile in length, became unique in that part of it lay in the state of Montana while the other part lay in the state of Idaho. Today, the tunnel, also known as Taft Tunnel, has not seen a train in more than 30 years although it is now part of the "Route of the Hiawatha" rail/trail.

This scene depicts the passenger's side view of a hi-rail vehicle as it approaches the west portal of the St. Paul Pass Tunnel at Roland, Montana on June 16, 1969.

Few rail lines, let alone railroads, have garnered such interest, intrigue, and awe as the Chicago, Milwaukee, St. Paul & Pacific Railroad's Pacific Coast Extension, even 30 years since it was abandoned. Unfortunately, the best engineered rail line through the rugged Cascades could not save it from the inept decision making of management at the time and it is now but weeds and trails, a vital transportation artery no longer available to shippers and the American economy.  In 1901 the first surveying work began and it was estimated the more than 1,400-mile western extension would cost the railroad around $45 million adding more than 25% to its total system mileage.

However, four years later this number was readjusted to $60 million. What made the extension so terribly expensive was partly due to the right-of-way costs. Unlike the Great Northern and Northern Pacific the CM&StP was not given free government land grants and had to both purchase all of its land from private landowners as well as take over a number of small, new, or floundering railroads across the region. Amazingly, in just three short years the entire extension had been completed and on May 19, 1909 a Golden Spike was driven at Garrison, Montana commemorating the opening of the new route.

This scene shows a Milwaukee Road superintendent calling the dispatcher at East Portal, Montana for permission to proceed on June 16, 1969. Directly behind the photographer is the entrance to the tunnel.

Surveying a route west of Butte, Montana began in earnest as early as November 1, 1904 when the first crews set out to begin the arduous process of laying out the best rail line through thousands of square miles of wilderness and steep, mountainous terrain using the standard tools of the day; transits, stadia rods, and barometers. The route surveyed over St. Paul Pass, which was ultimately chosen by the railroad, began in August 1906 and was completed in November of that year.

Surveying this section and the area it covered is somewhat staggering. The railroad estimated that for every one mile of grade which was ultimately chosen as part of the main line up to 4.5 miles was surveyed and documented. In total, between Butte and  the pass some 1,040 miles was surveyed with the actual main line covering those two points being only 230 miles in length.  Contract work for the building of the St. Paul Pass Tunnel was done by Winston Brothers Company of Minneapolis, Minnesota, which also handled much of the grading and construction between Missoula and the pass with the primary subcontract work carried out by contractors W.B. Cronk, A.D. McDougal & Company, Stewart & Welch, and Street & Lusk.

Another view from a hi-rail vehicle shows it approaching the trestle and bridge at Adair, Idaho on June 16, 1969.

Heading west from Missoula grading began in July 1906. Around this same time work was also started on the tunnel with its approaches completed in 1906 although heavy boring work did not begin until late 1907. Overall the gradient of the tunnel was kept at a manageable 1.7% while its overall length to span the Bitterroots was 1.66 miles! The tunnel was officially completed in December, 1908 giving the Milwaukee Road its second-longest tunnel across its Pacific Coast Extension.  For the railroad, which numbered its tunnels from east to west, the structure at St. Paul Pass was officially listed as #20.

Tunnel Specifications

Tunnel Number Milepost Height Width Length
#201750.119'14'-9"8,771 Feet


This photo was taken in the early 20th century depicting the construction of substation #13 at East Portal, Montana.

The tunnel also became known as Taft Tunnel due to its close proximity to the tiny hamlet of Taft, Montana near the state line.   However, the railroad came to know this location as East Portal, as it was the location of one of the substations after the line was electrified a few years following the tunnel's opening.   After the Milwaukee Road abandoned its Pacific Coast Extension in March, 1980 the tunnel sat dormant and empty for more than 20 years before it was officially "rededicated" on June 23, 2001 as part of the "Route of the Hiawatha" rail/trail. Today, the tunnel sees thousands of hikers and bikers annually.

Related Reading

Share Your Thoughts

Have your say about what you just read! Leave me a comment in the box below. Please note that while I strive to present the information as accurately as possible I am aware that there may be errors. If you have potential corrections the help is greatly appreciated.

Check out the website's digital book (E-book), An Atlas To Classic Short Lines, which features system maps and a brief background of 46 different historic railroads.



Related Reading

Upcoming/Notable Events



Thomas The Train




Streamliners At Spencer




The "Big Boy" #4014 Project




Fall Foliage Excursions, Where To Ride




"The Polar Express" Excursions, Dates And Locations


Popular Reading



Classic Railroads




Industry History




The Tycoons




The States




Maintenance Equipment




Important Infrastructure