Hoover Dam is a large concrete dam on the Colorado River in the southwestern United States, on the border between Arizona and Nevada, near Las Vegas. The project was begun in 1931, and when finished, in 1936, was the largest concrete structure in the world. It forms the reservoir known as Lake Mead, one of the largest man-made lakes in the world. Formerly called Boulder Dam, it was renamed after the American president, Herbert Hoover. It produces millions of megawatts of electricity by means of its hydroelectric generators and is a major tourist attraction.
The Colorado River is one of the major rivers in the western United States. For many years in the early 20th century, engineers investigated the area known as Black Canyon as a possible site for a hydroelectric dam that would create a reservoir and provide flood control for the powerful Colorado River. After the site was selected, the contract for building Hoover Dam was granted to a conglomerate of six major construction companies, called Six Companies, Inc. This new company completed the massive structure two years ahead of schedule, despite numerous obstacles, such as inhospitable desert working conditions and a near total absence of infrastructure in the region. Hoover Dam was dedicated by President Franklin Roosevelt in 1935.
Lake Mead, the large reservoir behind the dam, supplies fresh water to many regions of the southwestern United States as well as providing the mechanical energy used to turn the turbines within the dam that generate megawatts of electricity. Lake Mead is a favorite destination for boaters and fishermen in the region, and the entire area around it is designated as a National Recreation Area by the US government. For tourists wishing to see Hoover Dam, there is a visitor center and guided tours.
The art deco style of the 1930s can be seen in certain elements of the dam's construction. Four concrete towers on the reservoir side as well as spillways and power generating stations are still regarded as elegant examples of this architectural style, albeit on a huge scale. US highway 93 once ran along the top of Hoover Dam, but as traffic flow increased, an alternative was sought, and in 2010, a bypass project was completed that routed the highway over the longest concrete arch in the Western hemisphere, the Mike O'Callaghan-Pat Tillman Memorial Bridge, located some 1,600 feet (490 m) downstream from the dam.