Great Lakes Waterway

[2] Its principal civil engineering works are the Welland Canal between Lakes Ontario and Erie, and the Soo Locks between Huron and Superior.

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.

Together with the Saint Lawrence Seaway, the Waterway accommodates both ocean-going vessels and ore, grain, and coal-bearing lake freighters that 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 Saint Lambert, Quebec by larger ocean vessels.

Major ports on the Great Lakes Waterway include Duluth-Superior, Chicago, Detroit, Toledo, Cleveland, Two Harbors, Hamilton and Thunder Bay.