Papers of the New York State Governor, 1901-1904. Both incoming and outgoing correspondence, three items of which concern the selection of Ray Brook as the proposed site of the State Hospital for consumptives. Correspondence with Horatio Collins King, Anson G. McCook, John G. McCullough, Nathan L. Miller, Henry Codman Potter, and others.

New York State Governor, 1885-1891; U.S. Senator, 1891-1897. Collection contains incoming and outgoing correspondence (chiefly political), legal papers and memorabilia.

Papers of the Congressman from New York, United States minister to France, Vice-President of the United States, and Republican governor of New York State. Collection contains mostly incoming correspondence from clergymen, educators, financiers, journalists, and politicians. Some letters are addressed to Morton's executive secretary, Ashley W. Cole.

Papers of the U.S. Senator (1831-1833); New York State Governor (1833-1838); U.S. Secretary of War under James K. Polk (1845-1849); U.S. Secretary of State under Franklin Pierce (1853-1857). Incoming and outgoing letters concerning a wide variety of subjects such as the establishment of the State Geological Survey (G. W. Boyd, T. A. Conrad, John Delafield, Lardner Vanuxem); the use of volunteers for military service during the 1845-1848 war with Mexico (Silas Wright), the settlement of the New York-New Jersey boundary dispute (Andrew Jackson), the appropriation of public funds (Levi Woodbury, William C. Bouck), and the establishment of a State institution for the mentally handicapped (James B. Richards).