Andover is a town in Allegany County, New York, United States. The population was 1,634 at the 2020 census. The town is on the eastern edge of Allegany County and contains the village of Andover. The town's area was first settled circa 1795. The Town of Andover was established in 1824 from part of the town of Independence. The size of the town was incr…Andover is a town in Allegany County, New York, United States. The population was 1,634 at the 2020 census. The town is on the eastern edge of Allegany County and contains the village of Andover. The town's area was first settled circa 1795. The Town of Andover was established in 1824 from part of the town of Independence. The size of the town was increased in 1855 by a part of the town of Wellsville.