Many years after its construction, the Hoover Dam remains one of the largest in the world. Created under the auspices of the Colorado River Compact, its three objectives, in order of importance, were first the improvement of river and flood control and navigation; second, the channeling of water to the arid Southwest, and particularly California; and lastly, power generation. Although electricity was less important than the preceding two, it would become increasingly important as the population of California grew and power demand surged.

On this day, October 26, in 1936, the first electricity generator of the Hoover Dam turned on. Seven more would come on line in the years following, with the last one in 1961.

Together, the power lands of the dam were able generate 1.34 million kW of electricity, and with newer turbines installed in the 1980s the capacity jumped to over 2 million kW. That is enough to power a city of 750,000. California receives the lion’s share of the power, just about 57%, with the remainder divided between Nevada (23%) and Arizona (19%).