From the Morgan Sweeney Photograph Collection (PH-00228). Hoover Dam switchyard, circa 1950s. Stamp on the back reads, "Photograph by Bureau of Reclamation BCP 9187 Boulder Canyon Project Boulder City, Nevada."
Black and white image of the Hoover Dam tunnel construction site. There are four visible bridges over the Colorado River. Note: Boulder Dam was officially renamed Hoover Dam in 1947.