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.
Okanagan Basin
The Okanagan Basin spans two countries and comprises the basin of Okanagan Lake, the Okanogan River and tributary valleys such as that of the Similkameen and Chelan Rivers. In Canada the basin constitutes two distinct regions within British Columbia, the Similkameen Country to the west and the main Okanagan region running from the communities of Osoyoos in the south to Armstrong in the north – incorporating most of the three Okanagan regional districts and is usually known as "the Okanagan" or as the Okanagan Valley or the Okanagan Country. In the United States, the Okanogan Country is the western, lowland core of Okanogan County, which like its Canadian counterpart has a history and economy based on ranching, gold, fruit orcharding and vineyards, but the basin includes Lake Chelan and other flanking valleys. Communities in Washington's Okanogan Basin include Pateros, Omak, Okanogan, Oroville and Brewster.