“The building of Hoover Dam belongs to the sagas of the daring.”
- Oskar J.W. Hansen
In the early years of the 20th century, the rapid development of the southwestern United States was creating a high demand for electricity and water. Simultaneously, a series of catastrophic floods made it clear that the Colorado River needed to be dammed and controlled.
In 1922, the U.S. Reclamation Service settled on Black Canyon as the ideal location for a dam. They had initially chosen Boulder Canyon (unfortunately located on a seismic fault line), which gave the project its first name, Boulder Dam.
Congress authorized the project in 1928; construction began in 1931, under the direction of a consortium called Six Companies, Incorporated.
The Great Depression was in full swing, and tens of thousands of hopeful workers flocked to the dam site with their families, camping out in temperatures that reached 120 degrees Fahrenheit. At its peak, the project employed 5,251 people.
The first step: diverting the river away from the construction site. Three miles of diversion tunnels were dug on both sides of the river, and huge berms or “cofferdams" were built above and below the site.
With the riverbed dry, excavation began. Millions of tons of loose sediment and rocks were scraped away to reveal bedrock. The design called for an arch-gravity dam, which would transfer the crushing force of the water reservoir to the abutting canyon walls.
To make sure those walls were solid, workers known as “high scalers” had to rappel down them, hammering away anything loose. Falling rocks were a serious hazard, so the workers dipped their hats in tar and let them dry and harden — the first hard hats.