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 image of "Big Bertha," the Six Companies, Inc. motor transport used to haul workmen between Boulder City and Hoover Dam. This double-decker truck could haul 154 men. Note: Boulder Dam was officially renamed Hoover Dam in 1947.

Black and white image of fire fighters with the following printed description: "Government fire fighting equipment, Boulder City. The driver of the truck is Robert Hewes in charge of fire detail."

Black and white aerial image of several high scalers at work at the Hoover Dam construction site, specifically in the location for the Arizona-side intake towers. Note: Boulder Dam was officially renamed Hoover Dam in 1947.

Black and white image with the following printed description: "View showing extension work on Nevada Spillway Tunnel #2 at Hoover Dam. Work performed by Guy F. Atkinson Company of San Francisco, California." Note: Boulder Dam was officially renamed Hoover Dam in 1947.

Black and white image of Hoover Dam with the following printed description: "Looking upstream through Nevada spillway. Overflow weir under construction at right, completed section of channel lining and parapet at left." 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.