Boulder Dam, also known as Hoover Dam, is a concrete arch-gravity dam located on the Colorado River in Nevada. It was constructed between 1931 and 1936 and is one of the most iconic DAMS in the United States. The dam is made up of a combination of ROCK, STONE, and concrete, and is used to control flooding and provide hydroelectric power. The term 'Boulder Dam' is derived from the fact that the dam is made up of large boulders, which are held together by concrete.