Cascade Tunnel

The Cascade Tunnel refers to two railroad tunnels (original and its replacement) in the northwest United States, east of the Seattle metropolitan area in the Cascade Range of Washington, at Stevens Pass. It is approximately 65 miles (105 km) east of Everett, with both portals adjacent to U.S. Route 2. Both single-track tunnels were constructed by the Great Northern Railway.

The first was 2.63 miles (4.23 km) in length and opened in 1900 to avoid problems caused by heavy winter snowfalls on the original line that had eight zig zags (switchbacks). The current tunnel is a 7.8 miles (12.6 km) long and was put in service 88 years ago in early 1929, approximately 1.5 miles (2.4 km) south of and 500 feet (150 m) lower in elevation than the original. The present east portal is nearly 4 miles (6.4 km) east of the original's and is at 2,881 feet (878 m) above sea level, 1,180 feet (360 m) below the pass. The tunnel connects Berne in Chelan County on its east with Scenic Hot Springs in King County on its west and is the longest railroad tunnel in the United States.

The first tunnel began construction on August 20, 1897, and was completed on December 20, 1900. John Frank Stevens was the principal engineer on the interim switchback route (opened in 1893, with grades up to 4 percent) and the first Cascade Tunnel. Stevens Pass, located above the tunnels, was named after him.

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