Hoover Dam the change, stating, "I didn't know Hoover was that small a man to take credit for something he had nothing to do with." Hoover Dam was recognized as a National Civil Engineering Landmark in 1984. It was listed on the National Register of Historic Places in 1981, and was designated a National Historic Landmark in 1985, cited for its engineering innovations. Other sources Hoover Dam Hoover Dam is a concrete arch-gravity dam in the Black Canyon of the Colorado River, on the border between the U.S. states of Nevada and Arizona. It was constructed between 1931 and 1936 during the
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.