Collection consists principally of J. H. Horner's unpublished manuscript, "Wallowa River and Valley," dealing with regional history, as well as the history and cultural traditions of the Nimiipuu (Nez Percé) people. Other papers include correspondence (circa 1889-1985); legal documents (1898-1931); patents for window construction (1921-1922); and manuscript materials (undated). Horner's main correspondent is Otis Halfmoon of the Nimiipuu people, who collaborated on Horner's manuscript. The collection also includes a list of other contributors who assisted Horner in his research.