There are 13 US Post Offices in Jackson County serving a total of 21,754 residents equating to 1,673 residents per post office. It's estimated that approximately 34,722 packages are handled across the 13 county post offices annually. Jackson County is a county located in the U.S. state of Iowa. As of the 2010 census, the population was 19,848. The county seat is Maquoketa. The county was formed on December 21, 1837 and named after US President Andrew Jackson."