There are 8 US Post Offices in Henderson County serving a total of 6,638 residents equating to 830 residents per post office. It's estimated that approximately 10,595 packages are handled across the 8 county post offices annually. Henderson County is a county located in the U.S. state of Illinois. According to the 2010 census, it has a population of 7,331. Its county seat is Oquawka. Henderson County is part of the Burlington, IA\u2013IL Micropolitan Statistical Area."