There are 6 US Post Offices in Phillips County serving a total of 5,419 residents equating to 903 residents per post office. It's estimated that approximately 8,649 packages are handled across the 6 county post offices annually. Phillips County (standard abbreviation: PL) is a county located in the U.S. state of Kansas. As of the 2010 census, the county population was 5,642. The largest city and county seat is Phillipsburg."