Horatio Allen (1802-1889) was a noted civil engineer and inventor, who worked with the Delaware & Hudson Canal Company, the South Carolina Canal and Railroad Company, the Croton Aqueduct, and the New York & Erie Railroad. The bulk of his the papers is personal correspondence (1818-1864), and biographical materials collected by his family. Also included is a small collection of Allen's business papers, particularly concerning his work on the New York & Erie Railroad.

The Delaware, Lackawanna & Western Railroad was one of the largest and most prosperous anthracite mining and transporting companies in Pennsylvania. Their records consist of minutes of the DL&W and its two direct predecessors.

The Phoenix Steel Company began in the late eighteenth century as a manufacturer of cut nails. It later became a major producer of railroad rails and iron and steel structural members. Their records include minutes (1856-1929); stock ledgers; brief of title papers and property maps; legal and financial correspondence and tax papers; account books; and a works diary.