Merrimack River. The Merrimack River is a 117-mile-long 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 Gulf of Maine at Newburyport. From Pawtucket Falls in Lowell, Massachusetts, onward, the Massachusetts-New Hampshire border is roughly calculated as the line three miles north of the river. The Merrimack is an important regional focus in both New Hampshire and Massachusetts. The central-southern part of New Hampshire and most of northeast Massachusetts is known as the Merrimack Valley. Several U.S. naval ships have been named USS Merrimack and USS Merrimac in honor of this river. The river is perhaps best known for the early American literary classic A Week on the Concord and Merrimack Rivers by Henry David Thoreau. The Merrimack River in Pembroke, New Hampshire The Merrimack as it flows from Haverhill to its mouth in Newburyport, Massachusetts The etymology of the name of the Merrimack River-from which all subsequent uses derive, such as the name of the Civil War ironclad-remains uncertain. There is some evidence that it is Native American. In 1604 the natives of later New England told Pierre Dugua, Sieur de Monts, who was leading a colony of French language speakers to Acadia, of a beautiful river to the south. The French promptly pronounced its native name as Merremack. In 1605 Samuel de Champlain followed this lead, found the river and renamed it Riviere du Gas. The French and their name did not remain on the Merrimack. The natives dwelling along the river at the time of European exploration included the Agawam and Naumkeag on the lower reaches, the Pawtucket at Lowell, Massachusetts, the Nashua, Souhegan and Namoskeag around Manchester, New Hampshire, the Pennacook northward from Bow, New Hampshire, and the Winnepisseogee at the source, Lake Winnipesaukee. According to Joseph B. Walker, relying on Chandler Eastman Potter's The History of Manchester, Merremack contains the elements merruh and auke, and means the place of strong current,-a term not inappropriate, when we consider. the river's rapids. Potter was an authority on Native American affairs in colonial New England. By contrast, in A Week on the Concord and Merrimack Rivers, Henry David Thoreau implies that its name signifies the Sturgeon River. Walker goes on to cite spellings of Merimacke, Merimack and Merrimacke in the colonial records of Massachusetts, as well as the Merrimake and Merrymake of a 1721 land grant at Penacook, New Hampshire. William Wood's New England's Prospect of 1634 calls the river the Merrimacke and locates it eight miles beyond Agowamme. It hosts, he says, Sturgeon, Sammon and Basse, and divers other kinds of fish. Merrimac, Massachusetts, settled in 1638 and originally part of Amesbury, Massachusetts, was called West Amesbury until 1876, at which time it adopted its current name and spelling. Merrimack, New Hampshire, was incorporated in 1746, spelling its name Marrymac in the record of its first town meeting. It is referred to as Merrimac into the early 19th century: in the 1810 decennial census, it was spelled Merrimac, but in the 1820 census and afterwards, Merrimack. In 1914, US Congressman John Jacob Rogers petitioned that the official spelling be Merrimack. Prior to glaciation, the Merrimack continued its southward course far beyond the present day New Hampshire-Massachusetts border to enter the Gulf of Maine near Boston. Upon the glacier's retreat, debris deposited north of Boston filled the lower Merrimack Valley, redirecting the river into its current northeast bend at Lowell. The Neville archaeological site is located along the river's banks in New Hampshire. On the Merrimack River's banks are a number of cities built to take advantage of water power in the 19th century, when textile mills dominated the New England economy: Concord, Manchester, and Nashua in New Hampshire, and Lowell, Lawrence, and Haverhill in Massachusetts. At the mouth of the river is the small city of Newburyport. Prior to the construction of the Middlesex Canal, Newburyport was an important shipbuilding city, in a location to receive New Hampshire timber that had been floated downriver. The Merrimack River watershed covers 5,010 square miles in southern New Hampshire and northeastern Massachusetts. It is the fourth largest river basin in New England. The river begins in the city of Franklin, New Hampshire, at the confluence of the Pemigewasset and Winnipesaukee rivers.