Stretching from Montreal to Lake Superior, the system of locks and canals comprising the St. Lawrence Seaway enables access to the Great Lakes and the American Midwest. It is composed of two systems of locks. The first section links Montreal to Lake Ontario, with the first lock being St. Lambert, right at the outlet of the Port of Montreal and the last lock is Iroquois which lifts ships just about one meter. Between Lake Ontario and Lake Erie is the Welland Canal Section, lifting ships 99 meters through the Niagara Escarpment. Once at Lake Erie, Lake Huron, and Lake Michigan are readily accessible. Reaching Lake Superior requires transit through the Soo Locks, where ships are lifted an additional 7 meters.
For several reasons, including the increase of containerized cargo (most of which intercepted at the port of Montreal), ever-increasing competition between transport modes accompanying deregulation and trade liberalization, and, more importantly, the fact that maritime transportation remains the least expensive mode per tons shipped, the seaway corroborates its function as primarily a bulk cargo transit corridor.