Black and white aerial view of Black Canyon at Hoover Dam construction site. There are four visible bridges going over the Colorado River. Note: Boulder Dam was officially renamed Hoover Dam in 1947.
Caption at bottom of postcard reads: 150 man transport- Boulder Dam Bureau of Reclamation Photo." Boulder Dam was officially re-named Hoover Dam in 1947.
Postcard advertizing a souvenir cable section paperweight of the Boulder Dam- Los Angeles power line. Boulder Dam was officially re-named Hoover Dam in 1947.
An image of a film crew shooting penstock valves while they were open for the Boulder Dam dedication. Note: Boulder Dam was officially renamed Hoover Dam in 1947.
A-1 unit in Arizona wing of Boulder Dam powerhouse. Written with the image: "Started prodA-1 unit in Arizona wing of Boulder Dam powerhouse. Started producing power 10/12041 minus finish work of any kind." (photo by Bill Russell, USBR photographer from cab of upstream crane 300 ton.)