There are 4 US Post Offices in Morris County serving a total of 5,305 residents equating to 1,326 residents per post office. It's estimated that approximately 8,467 packages are handled across the 4 county post offices annually. Morris County (standard abbreviation: MR) is a county located in the U.S. state of Kansas. As of the 2010 census, the county population was 5,923. The largest city and county seat is Council Grove."