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.
Boreal forest of Canada
The boreal forest also has vast areas of wetland, particularly bogs and fens. Two wetland areas, the Hudson Bay Lowland and the Mackenzie River basin, are among the ten largest wetlands in the world. The boreal forest wetlands provide wildlife habitat (particularly for migratory birds), they maintain water flow in rivers, and they store significant amounts of carbon that otherwise would be released to the atmosphere.