The Ottawa River (French: Rivière des Outaouais, Algonquin: Kichi-Sìbì/Kitchissippi) is a river in the Canadian provinces of Ontario and Quebec. It is named after the Algonquin word "to trade", as it was the major trade route of Eastern Canada at the time. For most of its length, it defines the border between these two provinces. It is a major tributary of the St. Lawrence River and the longest river in Quebec.
