Illustration of Boulder Dam, later called Hoover Dam, with the view of lower portals and diversion tunnels. The caption reads: "Boulder Dam, looking upstream, showing Colorado River."

Illustration of Boulder Dam, later called Hoover Dam, construction. Caption reads: "A close-up, showing construction detail, Boulder Dam, Colorado River."

Illustration the of a train and people standing near it. Caption reads: "Union Pacific Miracle Train passing through a 30 foot intake pipe, Boulder Dam project."

Illustration "showing the immense concrete forms of Boulder Dam. Looking downstream, Colorado River."

Illustration of Boulder City, in which many houses and neighborhoods can be seen. The caption reads: "Boulder City, Nevada. A model city built to house the workmen engaged on the Boulder Dam [later known as the Hoover Dam] Project."

Postcard with an illustration of Boulder Dam view from Lookout Point. Boulder Dam was later renamed Hoover Dam.

Guest house and main building of Scotty's Castle. The National Park Service bought the private property in 1970 and it is now a part of Death Valley National Park. Site Name: Scotty's Castle (Death Valley, Calif.)