Poet and playwright. Correspondence (1921–1936), with some poetry enclosed; newspaper and magazine clippings (1926–1966); and manuscripts (1924–1932) by or about Riggs and his plays and poetry, as well as his relations with the artist communities of the University of Oklahoma, Taos and Santa Fe, New Mexico, Hollywood, California, and New York City. Correspondents include Betty Kirk Boyer and Willard Spud Johnson. The collection also includes playbills for a number of his plays.