List of longest rivers of Canada
Nine rivers in this list cross international boundaries or form them. Four—the Yukon, Columbia, Porcupine, and Kootenay—begin in Canada and flow into the United States. Five—the Milk, Pend d'Oreille, Saint Lawrence, Red, and Saint John—begin in the United States and flow into Canada. Of these, the Milk and the Kootenay cross the international border twice, the Milk leaving and then re-entering the United States, the Kootenay leaving and then re-entering Canada. The drainage basins of these nine rivers extend into both countries; in addition, the drainage basins of six others—the Fraser, Assiniboine, South Saskatchewan, Saskatchewan, Nelson, and Winnipeg—extend into the United States even though their main stems flow entirely within Canada.
Geography of Canada
The continental divide in the Rockies separates the Pacific watershed in British Columbia and Yukon from the Arctic and Hudson Bay watersheds. This watershed irrigates the agriculturally important areas of inner British Columbia (such as the Okanagan and Kootenay valleys), and is used to produce hydroelectricity. Major elements are the Yukon, Columbia and Fraser rivers.