Jackson Township is a township in Anderson County, Kansas, United States. As of the 2010 census, its population was 459. Jackson Township was established in 1857. Jackson Township covers an area of 34.1 square miles and contains no incorporated settlements, though the county seat of Garnett sits on the township's eastern border with Monroe Township. …Jackson Township is a township in Anderson County, Kansas, United States. As of the 2010 census, its population was 459. Jackson Township was established in 1857. Jackson Township covers an area of 34.1 square miles and contains no incorporated settlements, though the county seat of Garnett sits on the township's eastern border with Monroe Township. According to the USGS, it contains two cemeteries: Amish and Pleasantville.