THE HOOVER DAM stands on the Colorado River on the border of Arizona and Nevada and is one of the world's largest dams. Built between 1931 and 1936 by the U.S. Bureau of Reclamation and originally called the Boulder Dam it was re-named, in 1949, the Hoover Dam after the U.S. President, Herbert Hoover.

The dam is a major supplier of hydroelectric power and also provides for flood control, river regulation, and improved navigation of the Colorado River.Hoover Dam is a concrete arch-gravity dam, 726 ft (221 m) high and 1,244 ft (379 m) wide. Organised tours, which include the power plant, are available thoroughout the year.

Boulder City, situated close by, was built to house workers on the project.The first concrete for the dam was poured on June 6, 1933, and the last on May 29, 1935.
The dam was built in vertical columns with blocks varying in size from about 60 feet square at the upstream face of the dam to about 25 feet square at the downstream face. A cement and water grout was forced into the spaces between the columns to form a watertight 'one piece' structure. The Hoover Dam contains enough concrete in total to form a 16 foot (3 metre) wide, from San Francisco to New York City.
The entire project, including the hydro electric plant, cost $165 million to complete. The dam impounds Lake Mead, which is the largest reservoir in the United States, and forms part of Lake Mead National Recreation Area.
The lake extends approximately 110 miles upstream toward the Grand Canyon, covers around 250 square miles, and can store, on average, the entire flow of the river over a period of two years. Water is used to irrigate more than ten thousand acres (425,000 hectares) of land in California, Arizona and Mexico. Lake Mead a popular recreation area that attracts about ten million visitors each year for fishing, swimming, boating and water skiing.

Seventeen main turbines comprise the Hoover Dam power plant. The original turbines were all upgraded between 1986 and 1993 and can now supply 2,074,000 kilowatts of power, enough to serve well over a million people in Nevada, Arizona, and California. From 1939 to 1949 Hoover Dam power plant was the world's largest hydroelectric installation.
The revenue from the sale of power, employed originally to repay the cost of the project, is now used for the dam's operation and maintenance.

Below the dam the Colorado River continues its way through the gorge and down through Lake Havasu and Mexico to the sea.

Electricity is conducted through arid and inhospitable country via the grid system to locations in Nevada, Arizona and California.