There are 9 US Post Offices in Johnson County serving a total of 82,609 residents equating to 9,179 residents per post office. It's estimated that approximately 131,853 packages are handled across the 9 county post offices annually. Johnson County is a county located in the U.S. state of Iowa. As of the 2010 census, the population was 130,882 making it the fifth-most populous county in Iowa. The county seat is Iowa City, home of the University of Iowa. The county is named for Richard Mentor Johnson, the ninth vice president of the United States. Johnson County is included in the Iowa City, IA Metropolitan Statistical Area, which is also included in the Cedar Rapids-Iowa City Corridor Combined Statistical Area."