The Longest Railroad Tunnels In The United States

America's railroad tunnels are incredible feats of engineering. The Cascade Tunnel tops the list for longest in the country. This tunnel and the others listed below are ranked by portal-to-portal length. The ranking also includes active, historical, and major mainline rail tunnels across the U.S. Lengths are confirmed by each tunnel's official website and/or digital libraries and railway sources.

Cascade Tunnel

After the Great Northern Railroad laid tracks at the summit of Stevens Pass in the Cascade Mountains, train travel became possible in the area. The steep grade meant multiple switchbacks, and each switchback needed a thousand-foot spur. The switchbacks meant that trains traveled many miles only to move forward a couple of miles. The idea behind building the first Cascade Tunnel, starting in 1897, was to eliminate the switchbacks. The original Cascade Tunnel was 2.6 miles (4.2 kilometers) long and included seventeen snow sheds to protect the rails against avalanches.

These sheds could not, however, protect passengers against the deadliest avalanche in America's history in February 1910, which killed 96 people. The second tunnel, which replaced the old one after its completion in 1929, is 7.8 miles (12.5 kilometers) long. It sits at a lower elevation and carries a Burlington Northern and Santa Fe Railroad line through the Cascades. Today, the 'new' Cascade Tunnel is the longest railroad tunnel in the United States. It carries about 40 trains each day beneath Stevens Pass and runs below the Pacific Crest National Scenic Trail.

Flathead Tunnel

Montana's Flathead Tunnel is 7 miles (11.2 kilometers) long, and it was built between 1966 and 1969. Recognized as the second-longest railroad tunnel in America, it runs deep beneath Elk Mountain. The tunnel was built by hundreds of workers who used lasers and moved incredible amounts of earth. The last feet of dirt were blasted away by an explosion triggered by President Lyndon B. Johnson in 1968, and the tunnel finally opened on November 7, 1970. In 2018, plans were made to upgrade the Flathead Tunnel and other rail yards, at a cost of around $135 million. The tunnel still carries single-track lines. It includes reinforced concrete and features a mechanical fan system at the entrance to clear diesel engine fumes. It is an important link on BNSF Railway's northern cross-country route and handles daily freight traffic as well as Amtrak's Empire Builder.

Moffat Tunnel

Before the Moffat Tunnel was built below Colorado's Continental Divide, a snowbound rail crossing over Rollins Pass made travel difficult. The Moffat Tunnel is still active today and runs for 6.2 miles (10 kilometers) between Gilpin County and Grand County. At the time of its completion in 1928, it was the largest railroad tunnel in the Western Hemisphere. It was named after David Moffat, who tried to raise the needed funds to build the tunnel before he died in 1911. Unfortunately, the construction project was grim at times, with worker deaths overshadowing the innovative implementation of a pioneer bore doubling as a permanent aqueduct. Twenty-eight workers died throughout the construction period, with one accident killing six men at once due to a cave-in. Overall, the tunnel cost around $18 million to build, and when it opened, it shaved 173 miles off the trip between Denver and Salt Lake City. The first train traveled through the tunnel in February 1928, and today around 15 trains use the tunnel daily. It also carries passengers on the California Zephyr train. The State of Colorado owns the tunnel and leases it to Union Pacific Railroad.

Hoosac Tunnel

The construction of the Hoosac Tunnel in western Massachusetts saw even more worker deaths. The tunnel was the first major rock tunnel built in North America, constructed to link Boston with upper New York state. It runs through Hoosac Mountain and is 4.75 miles (7.6 kilometers) long. It was the longest tunnel in North America until 1916. While one million tons of rock were removed during the construction of the tunnel and 20 million bricks formed its lining, the construction period also saw the loss of nearly 200 lives. Most of the deaths were due to terrible working conditions, falling rocks, explosions, and scaffolding or ladder accidents. Workers staged a protest in 1865, but 14 more deaths followed this. The accident that killed the 14 men happened on October 17, 1867, when a candle ignited leaking lamp fuel. An explosion rocked the shaft the men were working in, trapping 13 at the base. A worker was lowered into the shaft to try and help them, but neither he nor the trapped workers ever returned to the surface.

Aptly nicknamed the Bloody Pit, the Hoosac Tunnel was originally built with two tracks. The tunnel was converted to a single track in the mid-1900s so modern freight cars could fit and officially opened in 1875 after around two decades of construction. Today, the tunnel is still active, running straight along the Deerfield River. It is part of the Pan Am Southern route and Norfolk Southern and CSX run freight through it. But it is not the trains that most people think about when the tunnel is mentioned. It is the ghosts that are rumored to haunt it.

Snoqualmie Tunnel

The Snoqualmie Tunnel was built between 1912 and 1914 by the Chicago, Milwaukee, St. Paul and Pacific Railroad. It was constructed as part of the company's line between Chicago and Seattle and replaced a temporary line over the Snoqualmie Pass. The tunnel crosses the Cascades three miles south of the pass, and its east portal lies at Hyak, where it is 2.2 miles (3.6 kilometers) long. The last train passed through the tunnel on March 15, 1980, and the track was completely abandoned by 1987. Today, the tunnel is part of the Palouse to Cascades State Park Trail, which stretches 250 miles. Visitors can walk the tunnel, which is tall and wide but very dark, especially in the middle. On the other end, there are picnic tables to use and views of the Cascades along I-90. The tunnel was renovated in 2011, and the structure has been reinforced. However, it is only open during the summer months because winter causes ice to form inside, making it unsafe. Even though the tunnel is no longer used for freight travel, it is still considered one of America's longest railroad tunnels.

Stampede Tunnel

Washington is also home to the Stampede Tunnel, which is still one of the longest railroad tunnels in the country. It was built by the Northern Pacific Railway between 1886 and 1888, is 1.86 miles (3 kilometers) long, and passes beneath the Stampede Pass. The construction of the tunnel was rushed to ensure a direct rail line to Puget Sound. Workers faced brutal winter conditions and severe water leaks while working in the wilderness. It took just over two years to finish the rock tunnel at a cost of just over $1 million. The tunnel, with its single railway track, operated as a freight line for many decades until Burlington Northern shut down the Stampede Pass route in 1983. BNSF Railway decided to spend $125 million in 1996 to reopen the tunnel. The restoration included lowering the floor and updating the supports to accommodate taller freight loads. The tunnel is still in active service for BNSF, allowing farm products and container freight to move across the Cascades.

America's Rail Tunnels Highlight The Best Of American Engineering

Building and maintaining these mountain tunnels back in the day allows freight to keep moving now. These passages are still great shortcuts for trains that carry heavy cargo up mountain ranges and through harsh weather. Rail companies continue to upgrade tunnels as needed, except for those that have been abandoned.

North America's longest railroad tunnels not only helped connect isolated regions by crossing mountain ranges, but also highlighted the best of what American engineering has to offer. Whether the earliest projects or the mid-century efforts, each tunnel solved problems and bottlenecks, using some of the best technologies of the time. Now, these massive engineering projects still keep trains running, keeping the economy moving.