Alpine Tunnel is a 1,772 ft (540 m) narrow gauge railroad tunnel located east of Pitkin, Colorado on the former Denver, South Park and Pacific Railroad route from Denver to Gunnison. At an elevation of 11,523 feet (3,512 m), it was the first tunnel constructed through the Continental Divide in Colorado, and according to the U.S. Forest Service "remains the highest railroad tunnel and the longest narrow gauge tunnel in North America." However, it did not last long in service. Construction began in January 1880 and was scheduled to last for six months but instead dragged on until July 1882, and the line was abandoned in 1910 due to minor damage in the tunnel.