There are 12 US Post Offices in Madison County serving a total of 94,485 residents equating to 7,874 residents per post office. It's estimated that approximately 150,809 packages are handled across the 12 county post offices annually. Madison County is a county located in the U.S. state of Indiana. As of 2016, the population was 160,000. The county seat is Anderson. Madison County is included in the Indianapolis-Carmel-Anderson, IN Metropolitan Statistical Area."