The North Branch of the Millers River is a 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 southwestern 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...

 and northern Massachusetts

Massachusetts

The Commonwealth of Massachusetts is a state in the New England region of the northeastern United States of America. It is bordered by Rhode Island and Connecticut to the south, New York to the west, and Vermont and New Hampshire to the north; at its east lies the Atlantic Ocean. As of the 2010...

 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 Millers River

Millers River

The Millers River is a river in northern Massachusetts, originating in Ashburnham and joining the Connecticut River just downstream from Millers Falls, Massachusetts...

, which flows west to 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...

, which in turn flows south to Long Island Sound

Long Island Sound

Long Island Sound is an estuary of the Atlantic Ocean, located in the United States between Connecticut to the north and Long Island, New York to the south. The mouth of the Connecticut River at Old Saybrook, Connecticut, empties into the sound. On its western end the sound is bounded by the Bronx...

, an arm of the Atlantic Ocean

Atlantic Ocean

The Atlantic Ocean is the second-largest of the world's oceanic divisions. With a total area of about , it covers approximately 20% of the Earth's surface and about 26% of its water surface area...

.

The North Branch rises in Rindge, New Hampshire

Rindge, New Hampshire

Rindge is a town in Cheshire County, New Hampshire, United States. The population was 6,014 at the 2010 census. Rindge is home to Franklin Pierce University, the Cathedral of the Pines, and part of Annett State Forest.-Native American inhabitants:...

, at the outlet of Island Pond. It flows west past East Rindge and Converseville to Lake Monomonac

Lake Monomonac

Lake Monomonac is an artificial lake that straddles the border between Rindge, New Hampshire and Winchendon, Massachusetts. It was created from a small pond in New Hampshire by the construction of dams on the North Branch of the Millers River, a part of the Connecticut River watershed.Lake...

. From the lake's outlet in Massachusetts, the North Branch flows south parallel to U.S. Route 202

U.S. Route 202

U.S. Route 202 is a highway stretching from Delaware to Maine, also passing through the states of Pennsylvania, New Jersey, New York, Connecticut, Massachusetts, and New Hampshire....

, joining the Millers River at Whitney Pond in Winchendon

Winchendon, Massachusetts

Winchendon is a town in Worcester County, Massachusetts, USA. The population was 10,300 at the 2010 census. Home to Winchendon State Forest, the town includes the villages of Waterville and Winchendon Springs....

.

The North Branch is 6 miles (9.7 km) long, 4 miles (6.4 km) of which are in New Hampshire, with 2 miles (3.2 km) in Massachusetts. If the channel length of 2.9 miles (4.7 km) through Lake Monomonac were included, the total length would be 8.9 miles (14.3 km).