Transportation of iron ore on the Great Lakes by Canadian vessels : hearings before the Committee on Merchant Marine and Fisheries, House of Representatives, Eightieth Congress, second session, on S.J. Res. 172, a joint resolution to authorize vessels of Canadian registry to transport iron ore between United States ports on the Great Lakes during 1948, and H.J. Res. 38, a joint resolution to authorize vessels of Canadian registry to transport iron ore between United States ports on the Great Lakes during the period from March 15, to December 15, 1949, inclusive. March 10, 1948.