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
Geology of Minnesota the Minnesota and Mississippi Rivers. Eventually, the ice sheet melted, and the Red River gave Lake Agassiz a northern outlet toward Hudson Bay. As the lake drained away its bed became peatlands and a fertile plain. Similarly, Glacial Lake Duluth, in the basin of Lake Superior, was dammed by a glacier; it drained down the ancient course of the Midcontinental Rift to the St. Croix River and the Mississippi. When the glaciers receded, the lake was able to drain through the Great Lakes to the Saint Lawrence River. Giant animals roamed the area. Beavers were the size of bears, and