Columbia River
Source Columbia Lake
Mouth Pacific Ocean
Length 2000 km
Basin Area 668,000 km²

The Columbia River is the largest river in Cascadia. The river's headwaters are in the Rocky Mountains of British Columbia, and it then flows first northwest and then south into Washington. The last portion of its route forms the border between Washington and Oregon, and its mouth is at Astoria on the Pacific coast. It has the greatest flow of any North American river draining into the Pacific.