Westborough is a town in Worcester County, Massachusetts, United States. The population was 18,272 at the 2010 census, in nearly 6,900 households. Incorporated in 1717, the town is governed now under the New England open town meeting system, headed by a five-member elected Board of Selectmen whose duties include licensing, appointing various administrative positions, and calling a town meeting of citizens annually or whenever the need arises.
According to the United States Census Bureau, the town has a total area of 21.6 square miles (56.0 km2), of which 20.5 square miles (53.1 km2) of it is land, and 1.1 square miles (2.8 km2) of it is water or 5.09 percent. Westborough is drained by the Sudbury and Assabet rivers. The town contains numerous bodies of water, including Lake Chauncy, Mill Pond, Lake Hoccomocco, and the Westborough Reservoir. Lake Chauncy is open to swimming, boating, and fishing, and has a public beach open to residents of Westborough and Northborough during the summer months. The average elevation of the town is approximately 300 feet (91 m).
Data from the U.S. Census of 2010 shows there were 18,272 people, 6,924 households, and 4,763 families residing in the town. The population density was 891.3 people per square mile (unofficial).