Archival objects in this container: Construction on the rock and gravel plant at the Hoover Dam construction site, approximately 1930-1935 Rock and gravel plant at the Hoover Dam construction site, approximately 1930-1935 Rock and gravel plant at the Hoover Dam construction site, approximately 1930-1935 Rock and gravel plant at the Hoover Dam construction site, approximately 1930-1935 Truck known as "Big Bertha," carrying 150 workers to the Hoover Dam work site, approximately 1930-1935 Six Companies, Inc. truck and employees at the Hoover Dam construction site, 1934 December 15 Six Companies, Inc. truck and employees at the Hoover Dam construction site, approximately 1930-1935 Railroad cars transporting structures to the Hoover Dam construction site, approximately 1930-1935 Railroad cars transporting structures to the Hoover Dam construction site, approximately 1930-1935 Workers with transport trucks coming up from the upper portals at the Hoover Dam construction site, approximately 1930-1935 Power site during Hoover Dam construction, approximately 1930-1935 Automobile parked next to a barge on the Colorado River in Black Canyon at the Hoover Dam construction site, approximately 1930-1935 Hoover Dam construction site from Black Canyon, near the Nevada spillway location, approximately 1930-1935 Construction on roads at the walls of Black Canyon at the Hoover Dam construction site, approximately 1930-1935 Construction on roads at the walls of Black Canyon at the Hoover Dam construction site, approximately 1930-1935 Construction on roads at the walls of Black Canyon at the Hoover Dam construction site, approximately 1930-1935 Construction on roads at the walls of Black Canyon at the Hoover Dam construction site, approximately 1930-1935 Construction on roads at the walls of Black Canyon at the Hoover Dam construction site, approximately 1930-1935 Construction on roads and a bridge across the Colorado River at the Hoover Dam construction site, approximately 1930-1935 Construction on roads at the walls of Black Canyon at the Hoover Dam construction site, approximately 1930-1935