A colored postcard showing an artist's representation of the construction site of Hoover Dam, previously known as Boulder Dam, in Black Canyon. Constructed in the 1930s, Hoover Dam crosses the Colorado River on the state line between Arizona and Nevada. Also considered to be an engineering wonder and the world's largest dam during its time of construction, Hoover Dam provides much-needed irrigation and hydroelectric power to the Southwest region of the United States. Transcribed onto the top border of the image: "Black Canyon, Boulder Dam Site."

A toilet and outhouse at a camp site at Tule Springs.

'Compiled by S.L. Schoff and J.E. Moore.' 'Geology generalized from geologic maps of the Nevada Test Site by Special Projects Branch, U.S. Geological Survey; of Lincoln County by Tschanz and Pampeyan (1961); and of Clark County by Bowyer, Pampeyan, and Longwell (1958).' United States Department of the Interior, Geological Survey. Prepared in cooperation with the U.S. Atomic Energy Commission.' 'TEI-838.' Scale 1:125,000 (W 116°00´--W 116°15´/N 37°15´--N 36°30´). Originally published as figure 1 in Chemistry and movement of ground water, Nevada Test Site / by Stuart L. Schoff and John E. Moore, published by the Geological Survey in 1964 as number 838 of the Trace elements investigations report.