On October 9, 1936, harnessing the power of the mighty Colorado River, Hoover Dam begins sending electricity over transmission lines spanning 266 miles of mountains and deserts to run the lights, radios, and stoves of Los Angeles.

Initially named Boulder Dam, work on the dam was begun under President Herbert Hoover’s administration but completed as a public works project during the Roosevelt administration (which renamed it for Hoover). When it was finished in 1935, the towering concrete and steel plug was the tallest dam in the world and a powerful symbol of the new federal dedication to large-scale reclamation projects designed to water the arid West. In fact, the electricity generated deep in the bowels of Hoover Dam was only a secondary benefit. The central reason for the dam was the collection, preservation, and rational distribution of that most precious of all western commodities: water.

Under the guidance of the Federal Reclamation Bureau, Hoover Dam became one part of a much larger multipurpose water development project that tamed the wild Colorado River for the use of the growing number of western farmers, ranchers, and city dwellers. Water that had once flowed freely to the ocean now was impounded in the 115-mile-long Lake Mead. Massive aqueducts channeled millions of gallons of Colorado River water to California where it continues to this day to flow from Los Angeles faucets and irrigate vast stretches of fertile cropland.

With Hoover Dam, the federal government set out to demonstrate that the aridity of a region once called the Great American Desert need be no serious obstacle to its full settlement and development. However, as rapidly growing western cities like Los Angeles, Las Vegas, and Phoenix today face increasing difficulties in obtaining the water they need, it remains to be seen if the Great American Desert might still dictate its own limits to western growth.