Chatham is a town in Barnstable County, Massachusetts, United States. Chatham is located at the southeastern tip of Cape Cod and has historically been a fishing community. First settled by the English in 1664, the township was originally called Monomoit based on the indigenous population's term for the region. Chatham was incorporated as a town on June 11, 1712, and has become a summer resort area. The population was 6,594 at the 2020 census and can swell to 25,000 during the summer months.