There are 4 US Post Offices in Humphreys County serving a total of 18,795 residents equating to 4,699 residents per post office. It's estimated that approximately 29,999 packages are handled across the 4 county post offices annually. Humphreys County is a county located in the U.S. state of Tennessee. As of the 2010 census, the population was 18,538. Its county seat is Waverly.