Contains materials from Kimball's years in the Southwest working on the Navajo Reservation. Includes correspondence and memoranda, interviews, research notes and subject files, newspaper clippings, printed books and pamphlets, reports, speeches and writings. Correspondence and memoranda includes officials from the Office of Indian Affairs, such as Commissioner John Collier, Superintendent E.R. Fryer and Supervisor John H. Provinse. Subject files, created by Kimball, contain materials regarding agriculture, land management, soil conservation, and Indian-government relations.