Jackson County is a county in the U.S. state of Kansas. Its county seat and most populous city is Holton. As of the 2020 census, the county population was 13,232. The county, first named Calhoun County for pro-slavery South Carolina Senator John C. Calhoun, was renamed in 1859 for President Andrew Jackson. The Prairie Band Potawatomi Indian Reservation, near the center of the county, comprises about 18.5% of the county's area.