Glenwood Canyon is a rugged scenic 12.5 mi (20 km) canyon in western Colorado in the United States. Its walls climb as high as 1,300 feet (400 m) above the Colorado River. It is the largest such canyon on the Upper Colorado. The canyon, which has historically provided the routes of railroads and highways through western Colorado, currently furnishes the routes of Interstate 70 and the Central Corridor between Denver and Grand Junction. The canyon stretches from near Dotsero, where the Colorado receives the Eagle River, downstream in a west-southwest direction to just east of Glenwood Springs, on the mouth of the Roaring Fork. Most of the canyon is in Garfield County, with the upper portion near Dotsero lying in Eagle County.