The Hoover Dam

Hoover Dam is a concrete arch-gravity dam in the Black Canyon of the Colorado River, on the border between the US states of Arizona and Nevada. It was constructed between 1931 and 1936, and was dedicated on September 30, 1935, by President Franklin Roosevelt. Its construction was the result of a massive effort involving thousands of workers, and cost over a hundred lives.  Such a large concrete structure had never been built before, and some of the techniques were unproven. The torrid summer weather and the lack of facilities near the site also presented difficulties. Hoover Dam impounds Lake Mead, and is located near Boulder City, Nevada. Although mainly intended to control floods and provide irrigation water, the dam's generators provide power for public and private utilities in Nevada, Arizona and California.