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.
Left to right shown are: Elwood Mead, Comm. Of Reclamation; Phil Swing, author of the bill, a member of House of Representatives from California; President Coolidge; U.S. senator Hiram Johnson, another author of the boulder Dam bill; Addison T. Smith, Chairman, Committee on Reclamation, House of Representatives; W.B. Matthews, General Counsel, Boulder Dam Association, Los Angeles, California. The occasion is the signing of the Boulder Dam bill, Dec. 21, 1928.