Black and white image of the construction phase of the Boulder Canyon Project, also known as Hoover Dam. This image features the first round of drilling to enlarge the upper portal of diversion tunnel No. 2. The welded steel "Jumbo Rig" mounted on the truck has 25 air drills on it. The swing shift crew standing next to the rig prepare for work. Note: Boulder Dam was officially renamed Hoover Dam in 1947.
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.
A black and white image of Secretary of the Interior, Ray Lyman Wilbur driving the last spike into the railroad from Las Vegas to the site of the Hoover Dam, signaling the beginning of construction. Also in the photograph are the following: Congressman William Eaton, of Colorado; Senator Key Pittman, Nevada; and Senator Samuel Shortridge. The celebration took place either at Boulder Junction (south of Las Vegas) or in Boulder City.