Southborough is a town in Worcester County, Massachusetts, United States. It incorporates the villages of Cordaville, Fayville, and Southville. Its name is often informally shortened to Southboro, a usage seen on many area signs and maps, though officially rejected by town ordinance. Atthe 2020 census, its population was 10,450 in 3,542 households. In 2021, 43% of land use is residential, with 35% open space, including a tenth of the town's area that is flooded by the Sudbury Reservoir. Light industrial land use is concentrated along main roads, primarily Massachusetts Route 9, and there are several small business districts in the villages and along Route 9. Southborough was first settled in 1660 and was officially incorporated in July 1727. Southborough was primarily a farming community until mills began to tap the small rivers that ran through the town. By the end of the 19th century, Southborough was home to the manufacture of plasters, straw bonnets, boots, and shoes, among other things.
In 1727, Southborough split off as the "south borough" of Marlborough, much as Westborough had split off from Marlborough in 1717, ten years before. In 1898, the Fayville Dam was constructed to produce several reservoirs to supply a growing Boston with water. As a result, manufacturing vanished, and Southborough did not see substantial growth until the high-tech boom of the 1970s. The Fay, Burnett, and Choate families had major impacts on the development of the town as it is today. St. Mark's Church, St. Mark's School, the Southborough Library, the Community House, and the Fay School were all built at least in part through the efforts of these families.