The Aroostook River originates at the confluence of Millinocket and Munsungan Streams in northern Maine north of Baxter State Park. It meanders for 100 miles east and northeast through Aroostook County — past Ashland, Presque Isle, Caribou and Fort Fairfield — before crossing the International Boundary into the Province of New Brunswick, where it enters the St. John River.
The upper 17 miles of the Aroostook from its origin downstream to Oxbow flow through undeveloped forest land. This section is noted for its wild brook trout fishery. During high water associated with spring runoff most anglers fish this section from a canoe. As the water recedes wading is also possible later in the season.
From Oxbow downstream past Masardis and Ashland to Washburn the river flows through forest and occasional fields. Early in the season it is possible to travel this section using a motor, making trolling for the native brook trout very popular among local anglers. Several access points along this 44-mile section make it possible to fish upstream and downstream using a single access point, or to take an extended fishing trip between two or more access points. As the water level recedes it is also possible to fish by wading at many locations in this section. During the summer trout will not be found throughout the river, as they often are during high water in the spring. Rather, they will be found in cool water areas associated with tributaries and springs.
From Washburn to the dam in Caribou, and then down to Fort Fairfield, the Aroostook flows for 37 miles through farmland and past development associated with the villages and towns along the way. Roads follow the river for most of this length. Again numerous access points make it possible to fish short stretches of river in a day, or take longer trips between two points.
Although the fishery in the Aroostook is primarily for wild brook trout, landlocked salmon are also occasionally caught. Because of the ongoing efforts to restore Atlantic salmon to the Aroostook River drainage all salmon caught must be released alive at once.