The West Branch of the Upper Ammonoosuc River is a 6.1 mile long (9.7 km) river

River

A river is a natural watercourse, usually freshwater, flowing towards an ocean, a lake, a sea, or another river. In a few cases, a river simply flows into the ground or dries up completely before reaching another body of water. Small rivers may also be called by several other names, including...

 in northern New Hampshire

New Hampshire

New Hampshire is a state in the New England region of the northeastern United States of America. The state was named after the southern English county of Hampshire. It is bordered by Massachusetts to the south, Vermont to the west, Maine and the Atlantic Ocean to the east, and the Canadian...

 in the United States

United States

The United States of America is a federal constitutional republic comprising fifty states and a federal district...

. It is a tributary of the Upper Ammonoosuc River

Upper Ammonoosuc River

The Upper Ammonoosuc River is a tributary of the Connecticut River that flows through Coös County in northern part of the northeastern U.S. state of New Hampshire...

 and part of the Connecticut River

Connecticut River

The Connecticut River is the largest and longest river in New England, and also an American Heritage River. It flows roughly south, starting from the Fourth Connecticut Lake in New Hampshire. After flowing through the remaining Connecticut Lakes and Lake Francis, it defines the border between the...

 watershed

Drainage basin

A drainage basin is an extent or an area of land where surface water from rain and melting snow or ice converges to a single point, usually the exit of the basin, where the waters join another waterbody, such as a river, lake, reservoir, estuary, wetland, sea, or ocean...

. For most of its length, it is within the White Mountain National Forest

White Mountain National Forest

The White Mountain National Forest is a federally-managed forest contained within the White Mountains in the northeastern United States. It was established in 1918 as a result of the Weeks Act of 1911; federal acquisition of land had already begun in 1914. It has a total area of...

.

The West Branch rises in the township of Kilkenny, New Hampshire

Kilkenny, New Hampshire

Kilkenny is a township located in Coos County, New Hampshire, USA. It was granted on June 4, 1774, containing about . As of the 2010 Census, the township had no inhabitants....

 in a basin on the east side of Mount Cabot

Mount Cabot

Mount Cabot is a mountain located in Coos County, New Hampshire. The mountain is the highest peak of the Pilot Range of the White Mountains. Cabot is flanked to the northeast by The Bulge, and to the south of Bunnell Notch by Terrace Mountain....

, the highest peak in the Pilot Range. The river flows east into Berlin

Berlin, New Hampshire

Berlin is a city along the Androscoggin River in Coos County in northern New Hampshire, United States. The population was 10,051 at the 2010 census. It includes the village of Cascade. Located on the edge of the White Mountains, the city's boundaries extend into the White Mountain National Forest...

, passing the Berlin National Fish Hatchery at York Pond before joining the Upper Ammonoosuc River.