There are 9 US Post Offices in Gibson County serving a total of 33,373 residents equating to 3,708 residents per post office. It's estimated that approximately 53,267 packages are handled across the 9 county post offices annually. Gibson County is a county located in the southwestern part of the U.S. state of Indiana. As of 2010, the population was 33,503. The county seat is Princeton. Gibson County is included in the Evansville, Indiana\u2013Kentucky Metropolitan Statistical Area."