Contains newspaper clippings, scholarly and magazine articles by Watson, photographs, notes and correspondence with the subjects and their relatives and acquaintances. (All correspondence with the subject of a folder is marked "Original Correspondence".) The files include information on 19th century western journalists, frontiersmen, explorers, Native Americans and Native American tribes, Remington forgeries, early western photographers, artists, and western writers. Among the individuals documented are D.F. Barry, Mathew Brady, Brave Bear, E.A. Brininstool, Badger Clark, Crazy Horse, G.A. Custer, Emmet Dalton, Geronimo, Valentine McGillycuddy, Lucullus Virgil McWhorter, Nelson A. Miles, Pawnee Bill, and Sitting Bull.

A portion of the photographs originally contained in the subject files have been removed and filed in the Edward E. Ayer Photograph Collection. They are housed in four boxes labelled "Elmo Scott Watson". Many photographs, together with supporting documentation, notes, and identifications, remain in the subject files. Negatives, including a few glass plates, also have been retained. There are also a number of early twentieth century catalogs of western photography studios.

Also of particular interest are the newspaper clippings contained in the subject files. They are particularly extensive from the Bozeman Courier, Kansas City Star, Saturday Evening Post, Kansas City Times, Rocky Mountain Empire Magazine, Black Hills Weekly, and St. Louis Post Dispatch.