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 the Colorado's major upper tributary, at Echo Park and Split Mountain. The 1956 Colorado River Storage Project Act authorized the purposes of "regulating the flow of the Colorado River, storing water for beneficial consumptive use, providing for reclamation of arid and semi-arid lands, providing flood control, and generating hydropower." The proposal for Glen Canyon Dam was most vocally supported by the state of Arizona, which wished to get Colorado River water to Phoenix and Tucson, located hundreds of miles away from the Colorado in the center of the state. Glen Canyon Dam would regulate river flow between Lee's Ferry and