There are 6 US Post Offices in Jackson County serving a total of 17,394 residents equating to 2,899 residents per post office. It's estimated that approximately 27,763 packages are handled across the 6 county post offices annually. Jackson County is a county located in the U.S. state of Wisconsin. As of the 2010 census, the population was 20,449. Its county seat is Black River Falls. Jackson County was formed from Crawford County in 1853. It was named for President Andrew Jackson."