The Columbia River Does Not Form a US-Canada Border

The Columbia River flows entirely within the United States for its lower 1,243 km (772 mi) — through Washington and Oregon. It does not serve as an international boundary.

Actual Course

• Source: Columbia Lake, British Columbia, Canada (Rocky Mountain Trench).
• Canadian reach: ~800 km north/northwest through BC (Revelstoke, Arrow Lakes, Trail).
• Crosses border: At 49th parallel near Waneta, BC / Northport, WA.
• US reach: Lake Roosevelt (Grand Coulee Dam) → Wenatchee → Tri-Cities (Richland/Kennewick/Pasco) → Wallula Gap → Portland/Vancouver → Pacific at Astoria.

Rivers That *Do* Form US-Canada Borders

• St. Croix River (Maine / New Brunswick)
• St. John River (short segment, Maine / NB)
• St. Lawrence River (NY / Ontario — partly)
• Rainy River (Minnesota / Ontario)
• Pigeon River (Minnesota / Ontario)
• Detroit River (Michigan / Ontario)
• St. Clair River (Michigan / Ontario)
• Niagara River (NY / Ontario)

Columbia Treaty Context

Columbia River Treaty (1964) between US & Canada governs flood control and hydropower coordination (Canadian storage: Duncan, Keenleyside, Mica dams). It's a water management treaty, not a boundary treaty.

The Columbia is a shared resource, not a dividing line.