Part of the largest river basin in the Pacific Northwest, the Flathead River starts in Canada and runs through parts of the United States.
The river is part of the Columbia River drainage basin, as the Clark Fork is a tributary of the Pend Oreille River, a Columbia River tributary. The Columbia River (Upper Chinook: Wimahl or Wimal; Sahaptin: Nch'i-Wana or Nchi wana; Sinixt dialect swah'netk'qhu) is the largest river in the Pacific Northwest region of North America. The largest tributary is the North Fork, which runs from the Canadian province of British Columbia southwards. Near West Glacier the North Fork combines with the Middle Fork to form the main Flathead River. Montana United States, Canada 
