Since the Walter Jessup administration in 1916, the President's Office has maintained an index of Presidential Correspondence in the form of a Kardex file to which name and subject entries are posted. A new alphabetical sequence is begun approximately each fiscal year. These cards files have been photocopied and a bound copy is available in the University Archives; these primary files are not yet available on-line. They are, clearly, essential to tracing correspondence on specific subjects.

The Kardex entries consist of the name or subject and reference to a folder number (which may change from year to year for a particular subject although in a short span of years it often remains the same). To find the current physical location of the referenced folder, readers must consult the photocopied Kardex entries, note the number of any folder they wish to review, and then determine from the list which follows the number of the storage box in which the folder has been placed.