Great Lakes Megalopolis the Chicago-Rochester corridor, starting at the Detroit River but continuing east beyond Lake Ontario along the St. Lawrence Seaway to Quebec City and the Gulf of St. Lawrence. Several corridors have interstate highways but no comprehensive passenger rail service. These highway routes pass through both core and fringe areas of the Great Lakes megalopolis. The upper Great lakes region has a marine corridor that connects Lakes Superior, Huron, and Michigan. However, this route does not include parallel Amtrak passenger rail or interstate highway service. I-70 follows the southern fringe of the megaregion. It runs from Kansas City MO to just
Great Lakes Waterway lake freighters to travel from the system's saltwater outlet to its far interior. The Waterway has larger locks and deeper drafts than the lower Seaway, limiting large freighters to the four lakes upstream of the Welland Canal and Lake Ontario and similarly restricting passage beyond the canal by larger ocean vessels. The two waterways are often jointly and simply referred to as the "St. Lawrence Seaway", since the Great Lakes, together with the St. Lawrence River, comprise a single navigable body of freshwater linking the Atlantic Ocean to the continental interior. Shipping channels separate upbound traffic from downbound traffic. The