Building Hoover Dam: A wonder of engineering

Updated 10:01 PM ET, Tue June 8, 2021
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It was September 1935 when President Franklin D. Roosevelt dedicated the massive Hoover Dam, a marvel of modern engineering when it was completed in a remote, unforgiving desert during the Great Depression. By harnessing the mighty Colorado River, the concrete structure on the Arizona-Nevada border provided electricity to the Southwest, helped irrigate 2 million acres and fueled the development of Los Angeles, Las Vegas and Phoenix. Here's a look at the dam and its construction. Bettmann/CORBIS
This image shows Black Canyon on the Colorado River before work started. During construction, the water was diverted around the dam site through four 50 feet in diameter tunnels, drilled through the canyon walls on each side of the river. Damming of the river created Lake Mead, now a popular recreation spot for boaters. General Photographic Agency/Hulton Archive/Getty Images
A man stands inside part of one of the dam's enormous turbines. Construction of the dam took less than five years and was completed in 1936. The American Society of Civil Engineers named Hoover Dam one of "Seven Modern Civil Engineering Wonders" in 1955, along with such landmarks as the Empire State Building and the Panama Canal. Landov
The dam was built in vertical columns of blocks that varied in size from about 60 feet square at the upstream face of the dam to about 25 feet square at the downstream face. An estimated 215 blocks make up the dam. Adjacent columns were locked together, like a giant Lego set, by a system of keys. library of congress
A Union Pacific Railroad train, carrying sections of the dam's steel gates, pulls out of Los Angeles en route to the dam site. Each gate section weighed about 36 tons, and when an entire gate was assembled it weighed 2,880 tons. Bettmann/CORBIS
Workers in 1932 construct a retaining wall to support the road leading over the top of the dam. Before the dam could be built, the government had to create a town, Boulder City, to house construction workers; build a seven-mile paved highway from Boulder City to the dam site; and construct 33 miles of railroad from the Union Pacific main line in Las Vegas. AP
When Hoover Dam was finished, it was the tallest dam in the world at 726 feet, although that record has since been eclipsed. The dam weighs more than 6.6 million tons and contains enough concrete to build a two-lane road from Seattle to Miami. Benjamin D. Glaha/Corbis
In its planning stages the dam was known as Boulder Dam after its original location, Boulder Canyon. But at a ceremony in 1930, Secretary of the Interior Ray Wilbur called it Hoover Dam, citing a tradition of naming dams after US presidents. Many Americans used both names interchangeably until 1947, when Congress passed legislation officially restoring the name to Hoover Dam. Dick Whittington Studio/Corbis
President Franklin D. Roosevelt views the dam for the first time at its dedication on September 30, 1935. At left is Walker Young, who was in charge of the project for the US Bureau of Reclamation. At right is a military aide to the President. AP
Workers rappel down a rock face during construction, which was often hazardous. A total of 21,000 men worked on the dam. Of those, 96 died at the dam site from falls, drowning, blasting, falling rocks, being struck by heavy equipment, truck accidents and other causes, according to the Bureau of Reclamation. Dick Whittington Studio/Corbis
Hoover Dam's water-intake towers rise 395 feet in the air. Through these towers flows the water that operates the dam's huge generators. The dam generates, on average, about 4 billion kilowatt-hours of hydroelectric power each year for use in Nevada, Arizona and California -- enough to serve 1.3 million people. The dam itself is a major tourist attraction, attracting nearly 1 million people for tours each year. AP