The Little River is a river in New Hampshire and Massachusetts in the United States. It is a tributary of the Merrimack River, part of the Gulf of Maine watershed. The Little River rises in Kingston, New Hampshire, flows south through Plaistow, and enters the city of Haverhill, Massachusetts, where it joins the Merrimack River. Most of the Little River's course is marked by suburban and urban development. See also List of rivers of Massachusetts List of rivers of New Hampshire References Tributaries of the Merrimack River Rivers of Essex County, Massachusetts Rivers of New Hampshire Rivers of Massachusetts Rivers of Rockingham County, New Hampshire