Principles involved in the signing of the Boulder Dam bill. L-R: Elwood Mead, Phil Swing, President Calvin Coolidge, Sen. Hiram Johnson, Addison T. Smith, and W.B. Matthews. Text on photo reads: "Public Service History Written as Boulder Dam Bill Is Signed. December 21, 1928. Elwood Mead, Commissioner of Reclamation. Phil Swing, M. C. Cali., Author Boulder Dam bill House of Representatives. President Coolidge. Senator Hiram Johnson, Author Boulder Dam bill in United States Senate. Addison T. Smith, M. C. Idaho, Chairman, Committee on Reclamation, House of Representatives. W. B. Matthews. General Counsel, Boulder Dam Association, Los Angeles."

Black and white image of officials from the Six Companies of San Francisco and the Bureau of Reclamation, as well as some local individuals, signing the contract to construct Hoover Dam (note: Boulder Dam was officially renamed Hoover Dam in 1947). Dr. Elwood Mead is signing the contract. Seated next to him is Henry J. Kaiser. Also identified in the photograph (in no particular order) are W.R. Armstrong, Walker Young, R.F. Walter, and Louis Crampton.