Men stand inside a diversion tunnel at the Hoover Dam. The Hoover Dam was called the Boulder Dam until 1947. "BDRA. NEV. 4.36 341" is written at the top of the photo. Site Name: Hoover Dam (dam)
View looking out of diversion tunnel, diameter 56' or more, inside finish 50'. Note on back: "Tunel is on Nevada side. Tunnels had compressed air lines and electricity installed Marion electric steam shovel. - W. A. Davis, 1992."