There are 3 US Post Offices in Cumberland County serving a total of 19,930 residents equating to 6,643 residents per post office. It's estimated that approximately 31,811 packages are handled across the 3 county post offices annually. Cumberland County is a county located in the U.S. state of Tennessee. As of the 2010 census, the population was 56,053. Its county seat is Crossville. Cumberland County comprises the Crossville, TN micropolitan statistical area.