At the onset of construction the dam location had been changed from Boulder Canyon to Black Canyon. Men in the need of work came to this desolate, wild, and hot area to earn a living during the United State's great depression. Arriving with families, a tent community was born. The life was rugged with no electricity, an average temperature of 119 degrees Fahrenheit (48 degrees Celsius) during the day, poor sanitary conditions and poor water set the stage for communities know as "Ragtowns." In order to improve their quality of life and to save people from disease, electricity came to the area and Boulder City was established. A school, church, post office and other supporting facilities where created for the families. 

Before the concrete arch-gravity type dam construction could begin the Colorado river needed to be diverted through diversion tunnels. This would allow the water to by pass the dam foundation site and later on to be used for the electric plant generators. Building tunnels directly through the canyon rock walls required dynamite, rock removal and structure for support to be built. The use of machinery within these tunnels created just as great a hazard, carbon monoxide poisoning, as drilling and blasting the rock. Once the first two tunnels where in place, cofferdams were built to divert the Colorado River. This allowed the dam construction to begin. (To the right is a drill rig used to construct the diversion tunnels.)

As in any construction project, the dam's base was a major factor in building an enduring structure. This required the men to excavate the mud and muck at the river bottom. With the aid of power shovels the men removed over half a million cubic yards to reach bedrock 40 feet below. Simultaneously the "high scalers" worked the canyon walls. Earning $5.60 a day, this was one of the highest paying jobs at the site. These men would blast the walls to create a smooth joining surface for the dam.

After much preparation on June 6, 1933 concrete began to be poured at the dam's base. (Left is the beginning of Hoover Dam's foundation.) The men poured 230 individual gigantic blocks of concrete to complete the base. This pouring process was necessary to allow the concrete to properly dry. On May 29, 1935 the last block was constructed, making the total concrete used for construction to be 3.25 million cubic yards. (This is enough concrete to pave a 16 feet wide highway from San Francisco to New York City!) With the completion of the dam's main construction the diversion tunnels were closed to start filling Lake Mead.

With the dam's building process complete, in 1935 Hoover Dam became the largest dam in the world.

(Photo courtesy of United States Department of the Interior Bureau of Reclamation - Lower Colorado Region)