Columbia County is a county located in the U.S. state of Arkansas. As of the 2020 census, the population was 22,801. The county seat is Magnolia. The county was formed on December 17, 1852, and was named for Christopher Columbus. The Magnolia, AR Micropolitan Statistical Area includes all of Columbia County. In 2014, voters overturned a 71-year-old prohibition against the sale of alcoholic beverages in the county.