On October 9, 1936, Hoover Dam's first hydroelectric generator began sending power across 266 miles of transmission line to Los Angeles, marking the practical payoff of one of the largest engineering projects of its era. Built on the Colorado River during the Great Depression by roughly 21,000 workers, the dam tamed catastrophic flooding, enabled irrigation across the arid Southwest, and became a symbol of American industrial capability at a moment of economic despair.
Construction had finished nearly two years ahead of schedule in 1935, an astonishing feat given the dam's scale: 6.6 million tons of concrete poured into a curved wall 726 feet high, enough material, boosters liked to boast, to pave a road from San Francisco to New York. More than a hundred workers died during construction from causes ranging from drowning to carbon monoxide poisoning in the diversion tunnels, though the once-popular legend that men were buried alive in the concrete pours is false—engineers poured in shallow interlocking blocks precisely to prevent such accidents and to let the concrete cure without cracking from heat.
When generator No. 1 came online, it began delivering power that Los Angeles had contracted for years earlier, part of a deal that helped finance the dam's construction. The Bureau of Reclamation project ultimately reshaped the American West, enabling the growth of Las Vegas, Phoenix, and greater Los Angeles through cheap electricity and reliable water. Named Boulder Dam until 1947, it was restored to honor Herbert Hoover, whose administration had championed the project despite his broader unpopularity during the Depression.
Key people: Herbert Hoover, Frank Crowe