Sunday, September 30, 2012
On September 30, 1935, President Franklin Roosevelt dedicated Boulder Dam, spanning the Colorado River between Arizona and Nevada. Begun in 1931, the gravity-arch dam curves upstream to direct water pressure against the canyon walls. Through 1936, 21,000 men built the structure (5,000 at any one time); 107 were killed. Workers turned a sleepy Las Vegas into today’s Sin City. Intended to prevent flooding and provide irrigation and hydroelectric power for California, Nevada and Arizona, the dam is 660 feet thick at its base, 70 stories high, made from more than 6.6 million tons of concrete, and generates 4 billion kilowatt-hours of hydroelectric power annually. Lake Mead behind it is one of the world’s largest man-made lakes. Congress saw fit to rename the dam after a much-reviled Herbert Hoover in 1947.