River in E North America. From ports on the Great Lakes it forms, with linking canals (which also give great hydroelectric capacity to the river), the St Lawrence Seaway for oceangoing ships, ending in the Gulf of St Lawrence. It is 745 mi/1,200 km long and is icebound for four months each year.
The river's source is Lake Ontario. In its upper course the St Lawrence includes the scenic Thousand Islands and forms the border between the Canadian province of Ontario and the US state of New York. It then enters the province of Québec and flows past Montréal and the city of Québec. Below the latter, it broadens to a maximum width of 90 mi/145 km when it empties into the Gulf of St Lawrence, an arm of the Atlantic Ocean. French explorer Jacques Cartier discovered the river 1535, and the first permanent colonial settlement (city of Québec) was established 1608 by Samuel de Champlain.
1. A North American river; flows into the Gulf of Saint Lawrence and the North Atlantic; Also called: St. Lawrence River.
2. Borough in Pennsylvania (USA).
3. Town in South Dakota (USA).