This series contains Alfred Traverse's professional correspondence with both individuals and organizations. The series is divided into two subseries; Subseries A: Scientific correspondence- individuals and Subseries B: Scientific correspondence-organizations. Subseries A makes up seven of the eight boxes. The folders are arranged alphabetically by last name, with each alphabetical letter's miscellaneous folder(s) appearing at the front of each section. Subseries B is filed at the end of the individuals section, and is in alphabetical order by organization. All correspondence is further arranged chronologically within each folder.

The individual correspondence spans from 1948 to 2001 and includes letters, printed emails, postcards, and a few photographs accompanied by their pertinent letter. The correspondence with organizations spans from 1952 to 1998 and may contain newsletters of organizations and various ephemera. Most of the folders contain a series of letters to and from Traverse. In some cases, the letters are filed not by the addressee's name, but by the name of the letter's most prominent subject. This is especially true in the case of correspondence regarding Traverse's students. Most of Traverse's correspondence is in regards to professional efforts he was involved in, from getting various books and papers published to paleobotanical digs to correspondence with and about his students. Many of them pertain to the workings of the American Association of Stratigraphic Palynologists (AASP) and the International Federation of Palynological Societies (IFPS).

[Connor Sites-Bowen compiled the inventory for Series 4 on 10 December 2004. It was revised by Jamie Shriver on 10 March 2005, and put online by Christi Thomas on 3 March 2026].