Construction of the Hoover Dam, on the Nevada-Arizona border, began on this day in history, July 7, 1930. It covers over 220 acres and is a National Historic Landmark.

During the time in the early 1920s when legislation was being crafted to authorize a dam on the Colorado River, Herbert Hoover served as Secretary of Commerce for President Warren Harding.

The Hoover Dam in Nevada was built two years ahead of schedule. (Lennox Mclendon/AP) On July 7, 1930, Interior Secretary Ray Lyman Wilbur sent an order to Elwood Mead, the commissioner of ...