Great Lakes Harbors Study: First Interim Report on Duluth-Superior Harbor, Minnesota and Wisconsin : Letter from the Secretary of the Army Transmitting a Letter from the Chief of Engineers, Department of the Army, Dated February 4, 1959, Submitting a Report, Together with Accompanying Papers and Illustrations, on Great Lakes Harbors Study--interim Report on Duluth-Superior Harbor, Minnesota and Wisconsin, Requested by Resolutions of the Committees on Public Works, U.S. Senate and House of Representatives, Adopted May 18, 1956, and June 27, 1956, Respectively