An image of the upstream face of Hoover Dam. Note: Boulder Dam was officially renamed Hoover Dam in 1947.

An image showing the upstream face of Hoover Dam; intake towers can be seen in Lake Mead. Note: Boulder Dam was officially renamed Hoover Dam in 1947.

An image of a project poster depicting the Hoover Dam when it was first planned to be built in Boulder Canyon. Later constructed in Black Canyon where less rock faults were found, Hoover Dam was built in the 1930s on the Colorado River between Arizona and Nevada. Note: Boulder Dam was officially renamed Hoover Dam in 1947.

An image of the Boulder Dam Power Decennial plaque, which was made for the ten year anniversary of Boulder Dam, renamed Hoover Dam in 1947. Depicted on the sign is an outline of the downstream face of the Hoover Dam, along with outlines of the state seals of Arizona, California, Colorado, Nevada, New Mexico, Utah, and Wyoming. Transcribed from text across the sign: "Boulder Dam, Power Decennial. Flood Control - Irrigation - Power. Saluting Boulder Dam On Its Tenth Year Of Commercial Power Production. 1936-1946. Honoring The People Of The Colorado River Basin States. Whose initiative brought forth Boulder Dam, making possible: The maximum utilization of the water resources of this great river system; The prevention of floods; The conservation of water; The availability of hydroelectric energy to a wide area."

An image showing Hoover Dam's upstream face and intake towers. Note: Boulder Dam was officially renamed Hoover Dam in 1947.

An image of the downstream face of Hoover Dam. Note: Boulder Dam was officially renamed Hoover Dam in 1947.

An image of the downstream face of Hoover Dam. Note: Boulder Dam was renamed Hoover Dam in 1947.