Correspondence, bills and accounts, contracts and other legal documents, inventories, reports, specifications and drawings, American and foreign patent papers, and related items, Horton's papers deal largely with the patenting, manufacture, and sale of his inventions, which include a clapboard gauge, a reaper and binder, a berry harvester, a combined hammer and nail feeder, and a basket-making machine; the bulk, which pertains to the perfection of the basket-making machine and the establichment (1895) of the Horton Basket Machine Company in Elmira, New York, includes correspondence with Rhesa G. DuBois, a Washington patent attorney who became secretary and manager of the company, and with the Robison Basket Company of Willoughby, Ohio, manufacturers of iron and steel products in Eastern cities, and purchasers of the machine; also, papers relating to the corporate organization of the firm, including legal agreements involving the Mergenthaler-Horton Basket Machine Company (1907) and the Federal Crate and Basket Company (1909). Horton's activities as a patent attorney are shown in his correpondence with upstate New York inventors of devices as varied as wagon brakes, pliers, mop wringers, wire stretchers, and cigar clippers; concerned mostly with patent searches and possible patent infringements, this part of the collection also includes correspondence with DuBois, who acted as Horton's representative in Washington.

Papers concerning Horton's other interests include correspondence, leases, tax bills, fire insurance policies, contractors' agreements, and other items relating to real estate he owned in Dundee and Elmira, New York (1896-1923); correspondence, tax receipts, and maps concerning his land in Michigan and the sale of white pines (1889-96); letters, stock certificates, and receipts pertaining to his investments in Colorado mining companies and other enterprises (1899-1924); letters, clippings, and printed forms having to do with the People's Party of Yates County and Horton's support of Populist aims (1888, 1891). Cashbooks, order books, journals, and accounts of business and personal expenses (1876-1931, 18 vols.); bankbooks, checkbooks, broadsides, other advertising materials, biographical data, diaries (1873-1932, 37 vols.), photographs, and miscellaneous personal items comprise the rest of the collection. Correspondents include C.B. Armstrong, C.F. Carrier, James O. Clephane, Isaiah Coleman, William Cronk, Silas C. Downey, George Fero, Francis Ellery Fitch, Stanley C. Flagg, Townsend Maccoun, James T. Robison, Frank Spencer, H.F. VanOrder, Ansley D. White, George Wilkin, W.A. Wilson; Barker, Rose & Gray, Browne & Sharpe Manufacturing Company, Cronk Hanger Company, Goble Brothers, LaFrance Fire Engine Company, Love, Chapman & Smith, Harris, McHenry & Baker, St. Catherine's Box & Basket Company, and Troy Malleable Iron Company. Also includes a carving of the Horton homestead on dry fungus, (MU-119).