Residents along the Colorado River were only too well acquainted with its near annual overflows and floods. Despite the best efforts to control it with channels and levees, it continued to have its way, so the U.S. Bureau of Reclamation to decided to build a dam. As a bonus, the finished structure would give the arid southwestern region a stable, year-round source of water.

On this day. July 7, in 1930, work began on the Boulder Dam, better known as the Hoover Dam, one of the largest construction projects in history. Six west-coast companies were involved in build the dam, with the total bid coming in at near $49 million.

Workers on the dam faced desert-climate temperatures, with highs reaching 120 outside and closer to 140 in the unventilated tunnels. Because of the scope of the project, many of the materials manufacturing plants were built on site. Steel, concrete and gravel were all created and mixed in a short distance away from the dam, and five thousand workers in twenty-one months erected a structure greater in volume than the largest Egyptian pyramid, which according to ancient history took 100,000 workers and twenty years.