The Knox River is a 2.5 mile long (4.1 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...

 located in western 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...

. The river is an inlet of Mascoma Lake

Mascoma Lake

Mascoma Lake is a lake in western New Hampshire, United States. Most of the lake is located within the town of Enfield, while a small portion is within the city of Lebanon, where it drains into the Mascoma River, a tributary of the Connecticut River....

, which drains by the Mascoma River

Mascoma River

The Mascoma River is a 31.6 mile long river located in western New Hampshire in the United States. It is a tributary of the Connecticut River, which flows to Long Island Sound. The Mascoma comprises two sections which are split by Mascoma Lake in the communities of Enfield and Lebanon...

 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...

 and ultimately 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...

.

The Knox River lies entirely in the town of Enfield, New Hampshire

Enfield, New Hampshire

Enfield is a town in Grafton County, New Hampshire, United States. The population was 4,582 at the 2010 census. The town includes the villages of Enfield, Enfield Center, Upper Shaker Village, Lower Shaker Village, Lockehaven, and Montcalm....

. It begins at the village of Fish Market as the outlet of George Pond and flows northwest through Enfield Center

Enfield Center, New Hampshire

Enfield Center is an unincorporated village in the town of Enfield in Grafton County, New Hampshire. It is a separate community from the much larger village of Enfield, which is located in the northern corner of the town....

 to the southeastern end of Mascoma Lake. The river is paralleled for its entire length by New Hampshire Route 4A.