Correspondence, diary, expedition journal, financial material, scientific notebook and sketches, photographs, published material, including articles and newspaper clippings, and scrapbooks. Correspondence (1854-1902) includes that of Alexander Agassiz, Charles E. Beecher, E.D. Cope, James D. Dana, J.S. Diller, G.K. Gilbert, G. Brown Goode, Asa Gray, Robert T. Hill, Anna Hyatt Huntington, Hyatt’s father, Alpheus Hyatt, Audella Beebe Hyatt, Jules Marcou, Harriet Randolph Hyatt Mayor, A.S. Packard, Charles Schuchert, and Charles Walcott.

Correspondence, incoming and outgoing (1860-1932); diaries; account books; notebooks; a partial autobiography; and sketches. Correspondents include Clara Carter Hyatt Coad, Mary E. Freeman, Anna Hyatt Huntington, Archer M. Huntington, Alpheus Hyatt, Leon Kroll, Alpheus Hyatt Mayor, and Harriet Randolph Hyatt Mayor.

Papers of the American railroad magnate and capitalist, whose financial interests included steamship, manufacturing, construction, and land companies. Philanthropist, trustee of the Hampton Normal and Agricultural Institute and supporter of Tuskegee Institute. Collection includes incoming correspondence (1856-1904); letterpress copybooks (1868-1901); legal and financial (including real estate) records (1797-1901); amd personal papers (1862-1901). Notable among the real estate records are documents relating to the furnishing and household expenses of Huntington's San Francisco residence, and records relating to the design, construction, decoration, furnishing, and maintenance of Huntington's palatial home on 57th St. in New York City.

Family correspondence and Civil War letters (1863-1898).