Correspondence, notes, addresses, lectures, diaries, relating primarily to his publications, the Interstate Commerce Commission, the University of Michigan, state and national politics, American history, constitutional questions, lecture engagements, and personal and family affairs; and photographs. Correspondents include: Henry C. Adams, Russell A. Alger, Alexis C. Angell, James B. Angell, Henry P. Baldwin, Simeon E. Baldwin, Levi L. Barbour, B.L. Baxter, Charles F. Beach, Jr., Josiah W. Begole, John.