The
Columbia River is the largest river in the
Pacific Northwest region of North America. The river
rises in the
Rocky Mountains of
British Columbia, Canada. It flows northwest and then south into the US state of
Washington, then turns west to form most of the border between Washington and the state of
Oregon before emptying into the Pacific Ocean. The river is long, and its largest
tributary is the
Snake River. Its
drainage basin is roughly the size of France and extends into seven U.S. states and a Canadian province.