Hoover Dam – Nevada/Arizona

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. Construction was the result of a massive effort involving thousands of workers and cost over one hundred lives.

Since about 1900, the Black Canyon and nearby Boulder Canyon had been investigated for their potential to support a dam. In 1928, Congress authorized the project, and construction began in 1931. Such a large concrete structure had never been built before, and some of the techniques were unproven. The dam was finally completed in 1936, more than two years ahead of schedule.

The Hoover Dam impounds Lake Mead, the largest reservoir in the United States by volume when full. The dam's generators provide power for public and private utilities in Nevada, Arizona, and California. Hoover Dam is a major tourist attraction; nearly a million people tour the dam each year.