An interior view of Boulder Dam's powerhouse; an unidentified man stands in front of one of the newly completed power generators. Boulder Dam was officially renamed Hoover Dam in 1947.

A view of the interior of Boulder Dam, as seen from a visitor viewpoint platform; a man leans against the railing, looking down at power generators below. Boulder Dam was officially renamed Hoover Dam in 1947.

An image of President Roosevelt in his car en route to the dedication of Boulder Dam (officially renamed Hoover Dam in 1947).

An image of President Franklin D. Roosevelt giving a speech to a crowd at the Boulder Dam dedication ceremony (officially renamed Hoover Dam in 1947).

A black and white image of several unidentified men and women associated with the Rotary Club attending the Boulder Dam decennial (officially renamed Hoover Dam in 1947).

An image of Rotary Club members attending a lunch near Boulde Dam (officially renamed Hoover Dam in 1947). Three unidentified men stand beside each other eating food and wearing chef hats.

The view of the Fortification Hill area of Lake Mead as a visiting boat zips across the lake's surface. Two women dressed in their bathing suits playfully wave to the camera from the deck of the boat, as other visitors aid in directing the boat's path. Transcribed on the side of the boat: "27-J-154."