| Southwest Branch Saint John River | |
|---|---|
| Origin | Maine–Quebec border |
| Mouth | Saint John River |
| Basin countries | United States and Canada |
| Mouth elevation | 1,050 feet (320 m) |
The Southwest Branch Saint John River is a 62.0-mile-long (99.8 km)[1] river in Maine and Quebec. The branch originates in Little Saint John Lake () on the international boundary between Saint-Zacharie, Quebec and Maine Township 5, Range 20, WELS. The branch forms the Canada – United States border as it flows northeasterly to a confluence with the Little Southwest Branch Saint John River in Maine Township 9, Range 18, WELS. The Southwest Branch flows briefly into Quebec () and then through Maine to its confluence with the Baker Branch Saint John River in Maine Township 9, Range 17, WELS. The Southwest Branch finally joins with the Northwest Branch to form the Saint John River.