There are 14 US Post Offices in Pike County serving a total of 16,683 residents equating to 1,192 residents per post office. It's estimated that approximately 26,628 packages are handled across the 14 county post offices annually. Pike County is a county located in the U.S. state of Illinois. According to the 2010 census, it had a population of 16,430. Its county seat is Pittsfield."