Tyngsborough was founded in 1675 by
Colonel Jonathan Tyng, and the Tyng Mansion House was one
of the oldest homes north of Boston. On February 23, 1809,
Tyngsborough was incorporated as a town, breaking from
Chelmsford, Dunstable, and the parishes in Billerica.
The Merrimack River watershed is
approximately 4,700 square miles (12,200 km2),
covering much of southern New Hampshire and a portion of
northeastern Massachusetts. The river is perhaps best known for the early American literary classic A Week on the Concord and Merrimack River by Henry David Thoreau.