Collection consists of Olsen's personal and business papers, and a variety of publications about New Mexico. Includes personal correspondence (1889-1947), newspaper clippings about Olsen (1920-1935), obituaries of prominent New Mexicans, certificates from several New Mexican Governors (1901-1933), the settlement of Olsen's estate (1953), papers of Olsen's brother-in-law E.V. Chavez (1879-1896), and catalogs of the New Mexico Spanish American Normal School at El Rito (1939-1941). Correspondence includes letters involving the Shormoyer family (1889- 1907), the Bryan Steam Corporation (1935-1941), and a 1902 duel between Paul Wunschmann and George W. Armijo. Materials concerning property in Carrizozo and Fort Sumner, New Mexico are also in the collection.

Some materials are in Spanish.