Frederick Samuel Dellenbaugh (1853-1935) was an artist, explorer, historian, writer. From 1871 to 1873, Dellenbaugh was a member of John Wesley Powell's Second Colorado River Expedition, serving as an artist and assistant topographer. He later became historian of the expedition and of the Colorado River. Dellenbaugh also served as artist of the 1899 Harriman Alaska Expedition, was a founder of the Explorers Club in New York, and authored books, articles and short stories about the Powell Expedition, Native Americans, and the American West.

The Dellenbaugh collection includes correspondence, diaries, notes, manuscripts, clippings, publications, drawings, photo albums, and photographs relating to Dellenbaugh's expedition experiences and studies of the Colorado River and the American Southwest. Expedition materials consist of correspondence, photographs of individuals, and articles by Powell and others. Books, articles, short stories, and poems by Dellenbaugh are present, as well as a typescript of 1861 reminiscences by Edward E. Ayer. Also included are photographs of Dellenbaugh's paintings, southwestern Native Americans, and travels; a few taken by E.O. Beaman and John K. Hillers. Correspondents include expedition members, publishers, geographic societies, U.S. government agencies, John Burroughs, Frederick Webb Hodge, William Henry Jackson, Ellsworth and Emery Kolb, Daniel T. MacDougal, Robert Stanton, Robert Taft, John K. Hillers, and William Wallace Bass. Personal materials include diaries dating from 1889-1935, estate papers, W. Norton Goddard family photo albums; and notes, photographs, and maps for a history of Cragsmoor, NY art colony, founded by Dellenbaugh.