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
Course of the Colorado River through the desert Lower Colorado River Valley (LCRV), where its character changes significantly from fast-flowing whitewater to a low gradient braided stream with a wide floodplain. Here, the Colorado River ranges in width from and from in depth. It becomes a losing stream, with a gradual reduction in volume both due to evaporation in the hot desert climate and massive diversions for irrigation, urban areas, industry and thermo-electric power generation. The average flow rate of at Davis Dam diminishes to just at the Mexican border. At Needles, California the Colorado is crossed by Interstate 40; shortly downstream it passes the