Correspondence, speeches, draft of unpublished writings including an unpublished memoir, legal records, financial records, scrapbook, printed matter, and other papers relating primarily to Caton's activities as a businessman and lawyer in Chicago and as associate and chief justice of the Supreme Court of Illinois. Documents his work as chief stockholder and director of the Illinois and Mississippi Telegraph Company, Illinois Starch Company, Oneida Solar Salt Company, and other business enterprises; investor in western mines; traveler; and author writing about nature studies and Illinois judicial affairs.

Correspondents include Thomas Basnett, Sidney Breese, Thomas D. Catlin, Seldon Churchill, W.C. Churchill, Ezra Cornell, Austin C. French, Melville Weston Fuller, George H. Gatiss, L. Howell, Josiah Macy's Sons, James F. Joy, Norman B. Judd, Joel A. Matheson, Henry O'Riley, Hiram Sibley, Nathan Smith, E.D.L. Sweet, Samuel Hubbel Treat, Lyman Trumbull, Pinkney Houston Walker, Horace White, Norman Williams, J.J.S. Wilson, and Caton family members including Caton's wife, Laura A. Caton, and his brother, William P. Caton.