The correspondence is divided into three subseries: A. From Carter; B. To Carter; and C. Between Others. The majority of the letters from Carter are typescript copies. These have been copied onto acid-free paper, and only those original letters which are either signed by Carter or contain his notes remain in the collection. The correspondence is arranged alphabetically by recipient or sender, except for the last subseries, which is arranged chronologically. Boxes and folders are numbered consecutively throughout the series. Cross-references appear among the entries. Many letters to Carter contain enclosures or Carter's sketches for his replies on the backs, and notes appear when this occurs.