In 1881, the narrow gauge mainline of the Denver and Rio Grande Western Railroad was built across Marshall Pass on the way from Denver to Salt Lake City. This railroad line was completed before the Denver, South Park and Pacific Railroad completed the Alpine Tunnel, so it was the first crossing of the continental divide in Colorado by any railroad. The line reached Sargents, Colorado in August 1881. By 1884, the line was complete from Ogden, Utah to Denver.