Great Lakes Waterway River between Huron and Erie. Usually, one or more U.S. Coast Guard icebreakers help keep the water passage open for part of the fall and early winter, although shipping usually ceases for two to three months thereafter. The Great Lakes Waterway is co-administered by the governments of Canada and the United States of America. The waterway allows passage from the Atlantic Ocean to the inland port of Duluth on Lake Superior, a distance of and to Chicago, on Lake Michigan, at . Together with the Saint Lawrence Seaway, the Waterway allows both ocean-going vessels and the ore, grain and coal-bearing
Lake Duluth Marquette County, Michigan. Once the ice receded to the east of the mountains, new outlets opened across the Upper Peninsula of Michigan, carrying the melt water into the Lake Michigan basin. Lake Duluth was lowered as lower lines drainage along the ice front. Eventually the water level reached that of Lake Algonquin. The body of water occupied the western part of the Lake Superior basin as well as the basins of Lake Michigan and Lake Huron and finally the eastern part of the Lake Superior basin. The eastern limits of Lake Duluth on the north coast of Lake Superior have