This series consists of materials related to Klotz's research on the history of Southern California, most notably the Riverside area. Materials in the series include Klotz's manuscripts for her books, Adobes, Bungalows, and Mansions of Riverside and Through the Doors of the Mission Inn; newspaper clippings, brochures, and research materials.

Major topics covered in the series consist of areas on which Klotz frequently focused her historical research, including historical buildings, local history and development, water and weather issues, local societies and organizations, and social life and customs.