Black and white image of the following individuals signing official contracts and deeds from the U.S. Bureau of Reclamation to Boulder City: Standing, from left to right: Joe Manix, Thomas White, M.D., Albert Franklin, and Morgan Sweeney; seated, from left to right: Lorraine Kautz, A. B. West, Robert Broadbent, and Milton N. Nathanson.

Black and white image of "Big Bertha" with the following printed description: Six Companies, Inc. motor transport hauling workmen between Boulder City and the dam. This double decked truck hauls 154 men.

Black and white portrait with the following printed description: John Wesley Powell - Winter of 1869.

Black and white portrait with the following printed description: Major John Wesley Powell - 2nd Director of Geological Survey (March 18, 1881 to June 7, 1894).

Black and white image of Herbert Hoover and several others touring the Boulder Canyon Project. The following printed description accompanies the image: "President Herbert Hoover and official party in Tunnel No. 2 during inspection tour of Boulder Canyon Project. Left to right: Construction Engineer W. R. Young, Bureau of Reclamation; Mr. Ritchey , Secretary to the President; Chief Engineer R. F. Walter, Bureau of Reclamation; Mrs. Hoover; President Hoover; Mrs. Wilbur; Secretary of the Interior R. L. Wilbur; E. O. Wattis, First Vice-President, Six Companies, Inc.; F. T. Crowe, Gen. Superintendent, Six Companies , Inc." Note: Boulder Dam was officially renamed Hoover Dam in 1947.

Black and white image of President Herbert Hoover and official party during an inspection tour of the Boulder Canyon Project. Note: Boulder Dam was officially renamed Hoover Dam in 1947.

Black and white image of Hoover Dam with the following printed description: "Thirty-foot-diameter-steel-penstock pipe set up from joint assembly at the Babcock and Wilcox Co. Plant." Note: Boulder Dam was officially renamed Hoover Dam in 1947.