The melting mile-thick glaciers of the Wisconsin Ice Age left the North American continent with a marvelous gift thousands of years ago. Great Lakes: Lake Superior, Lake Huron, Lake Michigan, Lake Erie, and Lake Ontario are freshwater lakes. These lakes stretch a thousand miles across the heartland of both the United States and Canada, from the westernmost tip of Lake Superior in Duluth, Minnesota, to the easternmost tip of Lake Ontario in Watertown, New York, creating nearly 9,500 miles of ocean-like shores.