There are 4 US Post Offices in Lewis County serving a total of 13,496 residents equating to 3,374 residents per post office. It's estimated that approximately 21,541 packages are handled across the 4 county post offices annually. Lewis County is a county located in the U.S. state of Kentucky. As of the 2010 census, the population was 13,870. Its county seat is Vanceburg. The county was founded in 1806 and named for Meriwether Lewis."