The Merrimack River (or Merrimac River, an occasional earlier spelling) 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. From Pawtucket Falls in Lowell, Massachusetts, onward, the Massachusetts–New Hampshire border is roughly calculated as the line three miles north of the river.