The Merrimack Valley is a bi-state region along the Merrimack River in the U.S. states of New Hampshire and Massachusetts. The Merrimack is one of the larger waterways in New England and has helped to define the livelihood and culture of those living along it for millennia. Major cities in the Merrimack Valley include Concord, Manchester, and Nashua in New Hampshire, and Lowell, Lawrence, and Haverhill in Massachusetts. The Valley was a major center of the textile industry in the 19th century.