The Six Companies, Inc. Hoover Dam Photograph Collection (1931-1935), consists of approximately 400 black-and-white photographic prints contained in two photograph albums and an additional twenty-one loose black-and-white photographic prints with ten corresponding photographic negatives.

The Helen J. Stewart Photographs depict the Stewart Family from approximately 1860 to 1950. The photographs primarily depict Helen J. Stewart and her children as well as the Stewart Ranch (also know as the Las Vegas Ranch) in Southern Nevada. The photographs include the early Las Vegas, Nevada town site, landscapes of Southern Nevada and the American Southwest, mines and mining camps, railroads and railroad workers, the Las Vegas Fort (also known as the Old Mormon Fort), hotels and early businesses in Las Vegas, Native Americans and Native American artifacts, and postcards.