The Hoover Dam is a concrete arch-gravity dam located on the Colorado River, between the states of Arizona and Nevada. It was constructed between 1931 and 1936 during the Great Depression and was dedicated on September 30, 1935, by President Franklin D. Roosevelt. The dam was named after President Herbert Hoover. It was the first major dam built on the Colorado River and is one of the most iconic landmarks in the United States. The dam is 726 feet high and 1, 244 feet long, and it impounds Lake Mead, the largest reservoir in the United States. The Hoover Dam is an important source of hydroelectric power, providing electricity to millions of people in the Southwest.