There are 6 US Post Offices in Cumberland County serving a total of 11,202 residents equating to 1,867 residents per post office. It's estimated that approximately 17,880 packages are handled across the 6 county post offices annually. Cumberland County is a county located in the U.S. state of Illinois. As of the 2010 census, the population was 11,048. Its county seat is Toledo. Cumberland County is part of the Charleston\u2013Mattoon, IL Micropolitan Statistical Area."