The Director's Office began keeping correspondence in specific categories in the mid-20th century. Any correspondence with dealers, donors, museums, etc. from earlier decades may be found in Director's general correspondence.

Museum Directors during this period were: Charles Nagel, Jr., 1955-1964; Charles E. Buckley, 1964-1975; James N. Wood, 1975-1980; James D. Burke, 1980-1999; Brent Benjamin, 1999-2021.