There are 8 US Post Offices in Johnson County serving a total of 51,108 residents equating to 6,389 residents per post office. It's estimated that approximately 81,574 packages are handled across the 8 county post offices annually. Johnson County is a county located in western portion of the U.S. state of Missouri. As of the 2010 census, the population was 52,595. Its county seat is Warrensburg. The county was formed December 13, 1834 from Lafayette County and named for Vice President Richard M. Johnson. Johnson County comprises the Warrensburg, MO Micropolitan Statistical Area, which is also included in the Kansas City-Overland Park-Kansas City, MO-KS Combined Statistical Area.