Business and personal correspondence account for about half of the material in the Howard Cox manuscript collection. Most of the correspondence consists of materials relating to agriculture and agricultural machinery. Most of the correspondents are manufacturing, distributing, or finance companies. Carbon copies of letters sent by Cox are included at the end of the correspondence section. The remaining correspondence is of a more general and personal nature and includes: letters from friends and relatives, letters concerned with land usage problems, and correspondence with World War I patriotic groups. Comprises 14 folders.