| Machias River | |
| Mouth Coordinates: | 46.6219°N -68.4215°W |
| Subdivision Type1: | Country |
| Progression: | Aroostook — St. John — |
The Machias River is a major tributary of the Aroostook River, flowing [1] through Aroostook County in the northern part of the state of Maine, USA. From the outflow of Big Machias Lake (46.6793°N -68.765°W) in Maine Township 12, Range 8, WELS, the river runs southeast and east to its confluence with the Aroostook in Ashland.