An image of Davis Dam. Located within Pyramid Canyon between Arizona and Nevada, Davis Dam was constructed on the Colorado River 67 miles downstream from Hoover Dam. Due to the Mexican Treaty of 1944, the United States was required to construct Davis Dam for regulation of water to be delivered to Mexico.

An image of Hoover Dam's outlet works at night. Note: Boulder Dam was officially renamed Hoover Dam in 1947.

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

An image of Boulder Dam, as seen from the Nevada side. 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".

Black and white image of the Hoover Dam tunnel construction site. There are four visible bridges over the Colorado River. Note: Boulder Dam was officially renamed Hoover Dam in 1947.

A painted photo depicting Lake Mead and Hoover (Boulder) Dam. Text on front of post card: "Lake Mead in Black Canyon, Boulder Dam", "Boulder Canyon Project of the Business of Reclamation"; Text on back of post card: "Lake Mead is quite narrow, just above Boulder Dam, yet more than 500 feet deep, where it is confined between the somber cliffs of Black Canyon gorge. Beyond the gorge the waters spread extensively over the desert valleys to form a vast lake 115 miles in length, with a shoreline of more than 550 miles - the largest man-made lake in the world. Comfortable cruisers make regular scheduled excursions on Lake Mead."