It’s the most famous dam in the world, and it was officially dedicated by President Franklin Roosevelt on this day, September 30th, 1935.

Originally, it was simply called “the Boulder dam”, after the Boulder Canyon, in which it was built. It was renamed for President Herbert Hoover in 1947.

The Dam was built to provide water for agriculture in Nevada and Arizona. It came at huge cost both in lives, and environmental impact. 112 men lost their lives during the construction efforts.

Downstream, the construction of the dam completely destroyed the natural habitats that had grown, for thousands of years, out of the Colorado river delta. Many species of plant, animal, and fish were impacted by it.

The dam cost hundreds of millions of dollars to build – but it has completely repaid for itself several times over by generating electricity for millions of Americans, as well as providing a supply of freshwater from the largest reservoir in America.

Today, it is still a working dam, and a major tourist attraction – about a million people come to see it annually.

The Hoover Dam, dedicated and opened on this day, September 20th, 1935.