Hoover Dam is colossal concrete arch-gravity dam in the Black Canyon on the Colorado River that was constructed during the Great Depression between 1931 and 1936. Formerly known as Boulder Dam from 1933 and dedicated by President Franklin D. Roosevelt in 1935, the dam was officially renamed the Hoover Dam by a joint resolution of Congress in 1947 after President Herbert Hoover. The Hoover Dam impounds Lake Mead, and the dam’s generators provide power for public and private utilities in Nevada, Arizona, and California. Hoover Dam is a major tourist attraction and sees almost a million visitors every year.