Hoover Dam Completed
The Hoover Dam was completed on the Colorado River, then the world's largest hydroelectric dam
March 01, 1935
Taming the Colorado River
Hoover Dam was completed on September 30, 1935, on the Colorado River at the border of Nevada and Arizona. At the time of its completion, it was the largest concrete structure and the largest hydroelectric power plant in the world. The dam stands 726 feet (221 meters) tall and stretches 1,244 feet (379 meters) across Black Canyon. It was built during the Great Depression as part of President Franklin D. Roosevelt's public works program, providing employment for thousands of workers from across the country. The dam holds back Lake Mead — the largest reservoir in the United States — which stores two years' worth of Colorado River flow.
Building in the Desert
Construction of Hoover Dam was a logistical triumph under brutal conditions. Summer temperatures in Black Canyon regularly exceeded 120°F (49°C). Workers lived in Boulder City, a new town built specifically for the project. Over 21,000 men worked on the dam during its construction. The concrete was poured in small interlocking columns to manage heat — if the dam had been poured as a single mass, the heat from chemical reactions would have taken 125 years to dissipate and cracked the structure. 112 workers died during construction, though myths about workers being entombed in the concrete are false. The dam was completed two years ahead of schedule.
Power for the American West
Hoover Dam's hydroelectric generators provide power to Nevada, Arizona, and California. When it was built, it could supply electricity to the entire American Southwest — a region that was then largely without reliable power. The dam made the modern development of Las Vegas, Phoenix, and Los Angeles possible by providing water and electricity. Lake Mead also provides drinking water for nearly 25 million people. Climate change and decades of drought have dramatically lowered Lake Mead's water levels in recent years, raising serious concerns about the region's long-term water supply. The dam that made the modern West possible now faces a modern crisis.