The Hoover Dam started transmitting electricity 226 miles to Los Angeles on this date  78 years ago, using the power of the Colorado River to generate hydroelectric power for the job, which it's been performing since October 9, 1936.

The dam was the largest concrete structure in the world when it was finished. It was intended to provide usable water to the arid desert Southwest, which it accomplished by diverting water from the Colorado into Lake Mead, which is the country's largest reservoir when full. The generation of electricity was a secondary benefit. During its construction, it also become a key public works project, providing thousands of jobs during the Great Depression. The work was hard and dangerous, and over 100 lives were lost during its construction. 

The dam was interchangeably called Boulder Dam or Hoover Dam during the 1930s and 1940s, as members of the Franklin Roosevelt administration, including FDR himself, tried to discourage associating the dam with Herbert Hoover, under whose administration its construction had begun. By 1947, Hoover was a less polarizing figure as memories of the Great Depression faded, and Congress officially named the dam after him.

Today, the Hoover Dam is a crucial source of water for thirsty livestock, crops, and people in Nevada, Arizona, and California. It also helps keep the region's most bustling cities moving, by providing electricity for Las Vegas, Phoenix, and Los Angeles. Continued population growth along with drought conditions could make water usage a growing problem in the region, but the Hoover Dam is a symbol of man's significant, if limited, power to take control in some of the most inhospitable settings.

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