Brewster is a town in Barnstable County, Massachusetts, United States, Barnstable County being coextensive with Cape Cod. The population of Brewster was 10,318 at the 2020 census. Initially settled in 1659, the Town of Brewster is named after Elder William Brewster, the religious leader of Plymouth Colony. Brewster is known as the "Sea Captain's Town" fo…Brewster is a town in Barnstable County, Massachusetts, United States, Barnstable County being coextensive with Cape Cod. The population of Brewster was 10,318 at the 2020 census. Initially settled in 1659, the Town of Brewster is named after Elder William Brewster, the religious leader of Plymouth Colony. Brewster is known as the "Sea Captain's Town" for its wealth of eighteenth and nineteenth century historic captain's homes, including the Cobb House, the current home of the Brewster Historical Society.