Baboosic Brook is a 12.7 miles (20.4 km) stream

Stream

A stream is a body of water with a current, confined within a bed and stream banks. Depending on its locale or certain characteristics, a stream may be referred to as a branch, brook, beck, burn, creek, "crick", gill , kill, lick, rill, river, syke, bayou, rivulet, streamage, wash, run or...

 located in southern 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

Tributary

A tributary or affluent is a stream or river that flows into a main stem river or a lake. A tributary does not flow directly into a sea or ocean...

 of the Souhegan River

Souhegan River

The Souhegan River is a tributary of the Merrimack River in the northeastern United States. long with a drainage area of , it flows north and east through southern New Hampshire to the Merrimack River....

, which flows to the Merrimack River

Merrimack River

The Merrimack River is a river in the northeastern United States. It rises at the confluence of the Pemigewasset and Winnipesaukee rivers in Franklin, New Hampshire, flows southward into Massachusetts, and then flows northeast until it empties into the Atlantic Ocean at Newburyport...

 and ultimately to the Gulf of Maine

Gulf of Maine

The Gulf of Maine is a large gulf of the Atlantic Ocean on the east coast of North America.It is delineated by Cape Cod at the eastern tip of Massachusetts in the southwest and Cape Sable at the southern tip of Nova Scotia in the northeast. It includes the entire coastlines of the U.S...

.

Baboosic Brook begins at the outlet of Baboosic Lake

Baboosic Lake

Baboosic Lake is a lake located on the border of Amherst and Merrimack, in Hillsborough County, New Hampshire. The lake drains into Baboosic Brook....

 in the town of Amherst, New Hampshire

Amherst, New Hampshire

Amherst is a town in Hillsborough County, New Hampshire, United States. The population was 11,201 at the 2010 census. Amherst is home to Ponemah Bog Wildlife Sanctuary, Hodgman State Forest, the Joe English Reservation and Baboosic Lake....

. The brook takes a winding course (east- and southward flow predominating) through the towns of Amherst, Bedford

Bedford, New Hampshire

-Demographics:As of the Census of 2000, there were 18,274 people, 6,251 households, and 5,125 families residing in the town. The population density was 556.6 people per square mile . There were 6,401 housing units at an average density of 195.0 per square mile...

, and Merrimack

Merrimack, New Hampshire

Merrimack is a town in Hillsborough County, New Hampshire, United States. The population was 25,494 at the 2010 census, making it the eighth-largest municipality in New Hampshire....

before ending at the Souhegan River near its outlet to the Merrimack River.

Tributaries include Joe English Brook, Pulpit Brook, McQuade Brook, and Riddle Brook, all entering from the north.