There are 4 US Post Offices in Phillips County serving a total of 4,722 residents equating to 1,181 residents per post office. It's estimated that approximately 7,537 packages are handled across the 4 county post offices annually. Phillips County is one of the 64 counties in the U.S. state of Colorado. As of the 2010 census, the population was 4,442. The county seat is Holyoke. The county was named in honor of R.O. Phillips, a secretary of the Lincoln Land Company, who organized several towns in Colorado."