These professional papers of R.A.C. Henry cover every phase of his career from 1911 to 1960. A significant percentage relates to the St. Lawrence Seaway, and covers the period 1920-1960; these files contain information on estimated costs, power and navigation development, canal systems, engineering problems, Canada-U.S. relations, Québec and Ontario hydro, the implications of the project for the Montréal area, and historical aspects. The remaining files likewise contain correspondence, reports, memoranda and notes. Topics covered include railways in Canada and Mexico, 1913-1932; canals, particularly Lachine, Welland, and Sault Ste Marie, 1913-1915; the Québec hydro-electric industry, 1922-1946; Defence Communications Ltd., ca 1949-1954; air transportation, 1944-1957; and various reports on general economic questions or the affairs of specific companies for which Henry was consultant.