Postcard with an illustration of Hoover Dam. The caption reads: "Boulder Dam, as it will look when completed, Colorado River."

Illustration of Hoover Dam as it was being built. The caption reads: "Looking upstream, Colorado River, Boulder Dam."

Handwritten description of provided on back of image: "Taken by Robert Corvan, 1933. Up-river side of Hoover Dam before Lake Mead was filled."

This series of photographs documents the historic water overflow at Hoover Dam as seen from the Arizona side of the dam. Taken in August of 1983, this overflow marked the first time the spillways were used during a flood. After initially being filled, the spillways were tested once in August of 1941.

Hoover Dam was originally called the Boulder Dam from 1933-1947, but was renamed the Hoover Dam by a joint resolution of Congress. Site Name: Hoover Dam (dam)

Illustration of Boulder Dam, later called Hoover Dam, with the view of lower portals and diversion tunnels. The caption reads: "Boulder Dam, looking upstream, showing Colorado River."

Form K, a group of construction workers, were the first to reach top of Boulder Dam while being built.