where does lake ontario end and the st lawrence river begin
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.