Hoover Dam 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 Great Depression and was dedicated on September 30, 1935, by President Franklin D. Roosevelt. Its construction was the result of a massive effort involving thousands of workers, and cost over one hundred lives. Originally known as Boulder Dam from 1933, it was officially renamed Hoover Dam, for President Herbert Hoover, by a joint resolution of Congress in 1947. Since about 1900, the Black
Glen Canyon Dam Sea. After this catastrophe, California and Arizona began to call for a dam to control the tempestuous river. In 1922, six U.S. states signed the Colorado River Compact to officially allocate the flow of the Colorado River and its tributaries. Each half of the Colorado River Basin – the Upper Basin, comprising Colorado, New Mexico, Utah and Wyoming – and the Lower Basin, with California and Nevada – was allotted of water annually, and a treaty between the U.S. and Mexico was signed in 1944 allocating to Mexico. The third lower basin state, Arizona, did not ratify the Compact until