Black Canyon of the Colorado Black Canyon of the Colorado The Black Canyon of the Colorado is the canyon on the Colorado River where Hoover Dam was built. The canyon is located on the Colorado River at the state line between Nevada and Arizona. The western wall of the gorge is in the El Dorado Mountains, and the eastern wall is in the Black Mountains of Arizona. The canyon formed about 15 million years ago during the Miocene Basin and Range uplift. Black Canyon gets its name from the black volcanic rocks that are found throughout the area. Just south of the Hoover Dam on
Glen Canyon Dam Bridge Glen Canyon Dam Bridge The Glen Canyon Bridge or Glen Canyon Dam Bridge is a steel arch bridge in Coconino County, Arizona, carrying U.S. Route 89 across the Colorado River. The bridge was originally built by the United States Bureau of Reclamation to facilitate transportation of materials for the Glen Canyon Dam, which lies adjacent to the bridge just upstream. The two-lane bridge has an overall length of with a deck above the river, making it the one of the highest bridges in the United States. The bridge was the highest arch bridge in the world when completed in 1959.