The downstream side of Hoover Dam.

A view from the Arizona side railroad tracks of open valves at Hoover Dam outlet works.

An image of Boulder Dam's crest and intake towers. Note: Boulder Dam was officially renamed Hoover Dam in 1947.

An image of guests standing outdoors at Boulder Dam's decennial event. Note: Boulder Dam was officially renamed Hoover Dam in 1947.

An image of guests standing outdoors at Boulder Dam's decennial event. Note: Boulder Dam was officially renamed Hoover Dam in 1947.

An image of guests standing outdoors at Boulder Dam's decennial event. Note: Boulder Dam was officially renamed Hoover Dam in 1947.

The face of Hoover (Boulder) Dam, taken from the downstream side of the dam on the Arizona side, May, 1947. The intake towers are visible in the background. The hydroelectric generators are visible in the foreground. During the years of lobbying leading up to the passage of legislation authorizing the dam in 1928, Hoover Dam was originally referred to "Boulder Dam" or as "Boulder Canyon Dam", even though the proposed site had shifted to Black Canyon. The Boulder Canyon Project Act of 1928 (BCPA) never mentions a proposed name or title for the dam. When Secretary Wilbur spoke at the ceremony starting the building of the railway between Las Vegas and the dam site on September 17, 1930, he named the dam "Hoover Dam", citing a tradition of naming dams after Presidents, though none had been so honored during their terms of office. After Hoover's election defeat in 1932 and the accession of the Roosevelt administration, Secretary Ickes ordered on May 13, 1933 that the dam be referred to as "Boulder Dam". In the following years, the name "Boulder Dam" failed to fully take hold, with many Americans using both names interchangeably and map makers divided as to which name should be printed. In 1947, a bill passed both Houses of Congress unanimously restoring the name to "Hoover Dam".