There are 29 US Post Offices in Champaign County serving a total of 216,697 residents equating to 7,472 residents per post office. It's estimated that approximately 345,873 packages are handled across the 29 county post offices annually. Champaign County is a county located in the U.S. state of Illinois. As of the 2010 census, the population was 201,081. It is the 10th-most populous county in Illinois. Its county seat is Urbana. Champaign County is part of the Champaign\u2013Urbana, IL Metropolitan Statistical Area. The twin cities of Urbana and Champaign are the only cities in the county and they nearly surround the campus of the University of Illinois at Urbana-Champaign."