There are 5 US Post Offices in Worth County serving a total of 2,264 residents equating to 453 residents per post office. It's estimated that approximately 3,614 packages are handled across the 5 county post offices annually. Worth County is a county located in the northwestern portion of the U.S. state of Missouri. As of the 2010 census, the population was 2,171. It is the smallest county in the state in population and, excepting the independent city of St. Louis, the smallest in total area. Its county seat is Grant City. The county was organized February 8, 1861 and named for General William J. Worth who served in the Mexican-American War."