The Hoover Dam is finished.

Hoover Dam, also known as Boulder Dam, is a concrete gravity-arch dam in the Black Canyon of the Colorado River, on the border between the U.S. states of Arizona and Nevada. The dam, located 48 km southeast of Las Vegas, is named after Herbert Hoover, who played an instrumental role in its construction, first as Secretary of Commerce and then later as President of the United States. Construction began in 1931 and was completed in 1936, over two years ahead of schedule. The dam & the powerplant are operated by the Bureau of Reclamation of the U.S. Department of the Interior. Listed on the National Register of Historic Places in 1981, Hoover Dam was designated a National Historic Landmark in 1985. Lake Mead is the reservoir created behind the dam, named after Elwood Mead, who oversaw the construction of the dam.

Before the construction of the dam, the Colorado River Basin periodically overflowed its banks when snow from the Rocky Mountains melted and drained into the river. These floods endangered downstream farming communities. In addition to essential flood control, a dam would make possible the expansion of irrigated farming in the parched region. It would also provide a dependable supply of water for Los Angeles and other Southern California communities.

One of the major obstacles for the project was determining the equitable allocation of the waters of the Colorado River. Several of the Colorado River Basin states feared that California, with its vast financial resources and great thirst for water, would be the first state to begin beneficial use of the waters of the Colorado River and therefore claim rights to the majority of the water. It was clear that without some sort of an agreement on the distribution of water, the project could not proceed.