The incoming correspondence of Vanderpoel, containing letters from friends, clients, and colleagues and dealing with personal and legal matters. Correspondents include Henry M. Alexander, William Allen Butler, John P. and William V. S. Beekman, G. W. Bulkey, Joseph H. Choate, Frederic R. Coudert, Lewis L. Delafield, Jay Gould, William D. F. Maurice, Edward Pierpont, J. Bryce Smith, John Van Alen, John and Thomas Van Buren, and Henry Vanorden. Letters of a personal and business nature from various family members include several from Aaron and John Vanderpoel and Lewis Oakley, his uncles, and from Henry C. Van Schaack, his father-in-law. There are approximately twelve manuscripts of essays and speeches by A. J. Vanderpoel while he attended Kinderhook Academy and New York University, as well as a few by other family members. Various documents including mortgages, deeds, indentures, agreements, and court records relate to Vanderpoel's law practice and to family property.