The Zimmerman Collection consists of correspondence and clippings relating to the establishment of Columbia (Calif.) State Historic Park (1934-1949); the restoration of the San Francisco Presidio (1938); the establishment of the Ina Coolbrith Park (San Francisco, 1946); the establishment of Laurel Hill Cemetery Park (San Francisco, 1940); and, the establishment of the John Muir-Kings Canyon National Park. It also contains minutes of the San Francisco Historic Sites Committee (1938) and documents relating to various landmarking projects in the San Francisco area (1933-1947).

During the 1930s and 1940s Mrs. Rheta L. Zimmerman was Historian of the California Club and the Yerba Buena Parlor (SF), Native Daughters of the Golden West. She was also a member of the San Francisco Historic Sites Committee (1938). Her primary interest was in California landmark preservation. She was involved in the creation of the Columbia State Historic Park (1934-1949), as well as in the restoration of the San Francisco Presidio (1938) and in the creation of small historic parks in San Francisco (1940-1946). Mrs. Zimmerman also spoke on San Francisco historic sites before service organizations and on the radio.

Collection is open for research.