In the fall of 1938, USC librarian Myrtle G. Hart began organizing the archival material that had collected in the Edward L. Doheny, Jr. Memorial Library. The collection steadily grew in size and importance with the able assistance of the head of the Doheny Library Reference Department, Helen Azdherian, and was moved several times within Doheny Library. The first University Archivist, Jack Beahan, served in that position in a part-time capacity from 1973 to 1976. He was succeeded in 1977 by Paul Christopher, who became USC's first full-time University Archivist in 1984 and supervised the collection's physical relocation to a facility of his design in the East Library Building in 1988 before his retirement in 1996. The Archives have continued to expand in its holdings and usage under the supervision of Claude Zachary and Susan Hikida.
Here's an article about the University Archives from the Southern California Alumni Review, October 1948.