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.
Sacramento River
The major drainage basins bordering that of the Sacramento are that of the Klamath in the north, the San Joaquin and Mokelumne to the south and the Eel River in the west. The Russian River also lies to the west and the endorheic (closed) Honey Lake and Eagle Lake basins to the north. On the east side are many endorheic watersheds of the Great Basin including the Truckee River and Carson River. Parts of the Sacramento watershed come very close to, but do not extend past, the border of California and Nevada.