Aerial view of Hoover Dam.

Aerial view of Hoover Dam.

Aerial view of Hoover Dam.

Aerial view of Hoover Dam.

Black and white image of the Young Presidents' Organization Convention Chairman, Dick Woodward (left), and Hoover Dam Project Manager, Frank Lord, greeting Bureau of Reclamation Commissioner, Ellis L. Armstrong, upon his arrival to a celebration held by the Young Presidents' Organization at the Hoover Dam powerhouse. The party for nearly 1,000 people was held on the roof. The visitors, all wearing hard hats, were the first to use this setting.

A colored postcard showing an artist's representation of the construction site of Hoover Dam, previously known as Boulder Dam, in Black Canyon. Constructed in the 1930s, Hoover Dam crosses the Colorado River on the state line between Arizona and Nevada. Also considered to be an engineering wonder and the world's largest dam during its time of construction, Hoover Dam provides much-needed irrigation and hydroelectric power to the Southwest region of the United States. Transcribed onto the top border of the image: "Black Canyon, Boulder Dam Site."

Black and white image with the following printed description: The late afternoon sun highlights the transmission lines from Hoover Dam as they sweep across the desert.