Carlisle is a town located northwest of Boston in Middlesex County, Massachusetts, United States. As of the 2020 U.S. Census, the town had a population of 5,237. English colonists first settled the area now incorporated as the town of Carlisle in 1651 on parcels of land of the neighboring towns of Acton, Billerica, Chelmsford and Concord. Carliā¦Carlisle is a town located northwest of Boston in Middlesex County, Massachusetts, United States. As of the 2020 U.S. Census, the town had a population of 5,237. English colonists first settled the area now incorporated as the town of Carlisle in 1651 on parcels of land of the neighboring towns of Acton, Billerica, Chelmsford and Concord. Carlisle became a district of Concord in 1780 and was incorporated as a town by an act of the legislature in 1805.