dam in Black Canyon on the Colorado River, at the Arizona-Nevada border, U.S. Constructed between 1930 and 1936 and originally named Boulder Dam, it was renamed in 1947 to honour President Herbert Hoover. Hoover Dam is the highest concrete arch dam in the United States. It impounds Lake Mead (Mead, Lake), which extends for 115 miles (185 km) upstream and is one of the largest manmade lakes in the world. The dam is used for flood and silt control, electric power, and irrigation and for domestic and industrial water supplies. Hoover Dam is 726 feet (221 m) high and 1,244 feet (379 m) long (along the crest) and has a power capacity of 1,345 megawatts and a volume of 4,400,000 cubic yards (3,360,000 cubic metres).