<Tr> <Td_colspan="2"> Map of the Saint Lawrence / Great Lakes Watershed </Td> </Tr> <P> The Saint Lawrence River (French: Fleuve Saint - Laurent; Tuscarora: Kahnawáʼkye; Mohawk: Kaniatarowanenneh, meaning "big waterway") is a large river in the middle latitudes of North America . The Saint Lawrence River flows in a roughly north - easterly direction, connecting the Great Lakes with the Atlantic Ocean and forming the primary drainage outflow of the Great Lakes Basin . It traverses the Canadian provinces of Quebec and Ontario, and is part of the international boundary between Ontario, Canada, and the U.S. state of New York . This river also provides the basis of the commercial Saint Lawrence Seaway . </P> <P> The Saint Lawrence River begins at the outflow of Lake Ontario and flows adjacent to Gananoque, Brockville, Morristown, Ogdensburg, Massena, Cornwall, Montreal, Trois - Rivières, and Quebec City before draining into the Gulf of Saint Lawrence, the largest estuary in the world . The estuary begins at the eastern tip of Île d'Orléans, just downstream from Quebec City . The river becomes tidal around Quebec City . </P> <P> The Saint Lawrence River runs 3,058 kilometres (1,900 mi) from the farthest headwater to the mouth and 1,197 km (743.8 mi) from the outflow of Lake Ontario . These numbers include the estuary; without the estuary the length from Lake Ontario is ca . 500 km (ca . 300 mi). The farthest headwater is the North River in the Mesabi Range at Hibbing, Minnesota . Its drainage area, which includes the Great Lakes, the world's largest system of freshwater lakes, is 1,344,200 square kilometres (518,998.5 sq mi), of which 839,200 km (324,016.9 sq mi) is in Canada and 505,000 km (194,981.6 sq mi) is in the United States . The basin covers parts of Ontario and Quebec in Canada, parts of Illinois, Indiana, Minnesota, New York, Ohio, Pennsylvania, Vermont, and Wisconsin, and nearly the entirety of the state of Michigan in the United States . The average discharge below the Saguenay River is 16,800 cubic metres per second (590,000 cu ft / s). At Quebec City, it is 12,101 m / s (427,300 cu ft / s). The average discharge at the river's source, the outflow of Lake Ontario, is 7,410 m / s (262,000 cu ft / s). </P>

Where does lake ontario end and the st lawrence river begin
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