The St. Lawrence River forms part of the boundary between Canada and the United States and connects the Great Lakes with the Atlantic Ocean. This informative book follows this important commercial waterway across the provinces of Ontario and Quebec to where it reaches the Gulf of St. Lawrence. Once a main route of the fur and timber trades, the St. Lawrence Seaway today—a system of canals, dams, and locks—lets seagoing ships travel all the way to Lake Superior. The river is also important as a source of electric power and a home to abundant wildlife. In addition, about one-fourth of Canada's population lives in the St. Lawrence Valley.