The St. Croix River is a river in northeastern North America, 71 miles (114 km) in length, that forms part of the Canada–United States border between Maine (U.S.) and New Brunswick (Canada). The river rises in the Chiputneticook Lakes and flows south and southeast, between Calais and St. Stephen. It discharges into Passamaquoddy Bay, in the Bay of Fundy.
The Aroostook River is a 112-mile-long (180 km) tributary of the Saint John River in the U.S. state of Maine and the Canadian province of New Brunswick. Its basin is the largest sub-drainage of the Saint John River.
The Allagash River is a tributary of the Saint John River, approximately 65 miles (105 km) long, in northern Maine in the United States. It drains in a remote and scenic area of wilderness in the Maine North Woods north of Mount Katahdin. The name "Allagash" comes from the Abenaki language, a dialect of the Algonquin languages, spoken by the Penobscot Tribe The word, /walakéskʸihtəkʸ/, means "bark stream".
The Piscataquis River is a major tributary of the Penobscot River, found in Piscataquis County, Maine, United States. It starts from the confluence of its East Branch and West Branch in Blanchard. The river flows in a mostly eastern direction until it meets the Penobscot at Howland. It is approximately 65 miles (105 km) in length.
The Union River is a 21.9-mile-long (35.2 km) river that runs through Ellsworth, the county seat of Hancock County in eastern Maine. In the colonial era, it was known as the Mount Desert River.
The Back River is a short tributary of the Meduncook River in Friendship, Maine. From its source, the river runs 2.7 miles (4.3 km) south to the estuary of the Meduncook.
The Back River is a tributary of the Saint George River in Knox County, Maine. From its source in Far Meadow in Cushing, the river runs 10.7 miles (17.2 km) north, through South and North Ponds, to its confluence with the Saint George in Warren.
The Dead River is a tributary of the Saint George River in the U.S. state of Maine. From the outflow of Newbert Pond in Appleton, the stream runs 3.1 miles (5.0 km) northeast to its confluence with the Saint George River in Searsmont.
The Ducktrap River is a river in Waldo County, Maine. From the outflow in Tilden Pond in Belmont, the river runs 10.0 miles (16.1 km) southeast, through Camden Hills State Park, to West Penobscot Bay in Lincolnville.
The East Branch Oyster River is a tributary of the Oyster River in Knox County, Maine. From its source in Rockland, the stream runs 4.8 miles (7.7 km) southwest to its confluence with the main stem of the Oyster River, on the border between Warren and Thomaston.
The East Branch Penobscot River is a 75.3-mile-long (121.2 km) tributary of Maine's Penobscot River. It flows in Piscataquis County and Penobscot County.
The East Branch Sebasticook River is a tributary of the Sebasticook River in central Maine in the United States. It is part of the Kennebec River watershed. From the outflow of Lake Wassookeag in Dexter, the river runs about 12.7 miles (20.4 km) south to Sebasticook Lake. From the outflow of the lake in Newport, the river runs about 9.5 miles (15.3 km) southwest to its confluence with the Sebasticook in Detroit.
The Little River is a short river in Waldo County, Maine. From its source in Belmont, the river runs 8.0 miles (12.9 km) east to Belfast Bay, on the border between Belfast and Northport.
The Medomak River, historically known as the Muscongus River, is a 40-mile-long (64 km) river in Maine. From its source in Liberty, the river winds 32 miles (51 km) south to the head of its tidal river estuary in Waldoboro, then about 8 miles (13 km) south to Bremen. The river flows through Hockomock Channel into the head of Muscongus Bay. Medomak is Abenaki for "place (river) of many alewives".
The Meduncook River is a 7-mile-long (11 km) river in Knox County, Maine. From its source in Friendship, the river runs about 1 mile south to the head of its estuary, then about 6 miles southwest to Muscongus Bay. The estuary forms part of the border between Friendship and Cushing.
The Mill River is a tributary of the Saint George River in Thomaston, Maine. From the confluence of Branch Brook and Meadow Brook, the river runs 2.7 miles (4.3 km) south to the head of the estuary of the Saint George.
The North Branch Penobscot River is a river in Somerset County, Maine. From its source at the outlet of Little Bog about 10 miles (16 km) east of the Canada–United States border in Maine Township 6, Range 17, WELS, the river runs 27.8 miles (44.7 km) southwest and southeast to its drowned confluence with the South Branch of the Penobscot River in Seboomook Lake in Pittston Academy Grant.
The Stillwater River is an 11.5-mile-long (18.5 km) side channel of the Penobscot River in Maine. From its source in Old Town, the Stillwater runs 2.3 miles (3.7 km) northwest along the northeast side of Orson Island, the site of the Penobscot Indian Reservation. It then runs 9.2 miles (14.8 km) south along the west sides of Orson and Marsh islands, over three dammed falls. The stream rejoins the main stem of the Penobscot in Orono.
The West Branch Mattawamkeag River is a 52.6-mile-long (84.7 km) tributary of the Mattawamkeag River in Maine. From its source in Maine Township 6, Range 6, WELS, the river runs 10 miles (16 km) northeast by Pleasant Lake and through Mud Lake and Rockabema Lake, then 42 miles (68 km) south and southeast through Upper Mattawamkeag Lake and Mattawamkeag Lake to its confluence with the East Branch Mattawamkeag River in Haynesville, about 10 miles (16 km) west of the Canada–United States border.
The West Branch Pleasant River is a 36.1-mile-long (58.1 km) tributary of the Piscataquis River in Piscataquis County, Maine. From a location north of Fourth West Branch Pond in Shawtown, the river runs about 18 miles (29 km) counterclockwise around the White Cap Mountain massif, then about 18 miles (29 km) southeast to its confluence with the East Branch of the Pleasant River in Brownville.
