There are 7 US Post Offices in Jewell County serving a total of 2,890 residents equating to 413 residents per post office. It's estimated that approximately 4,613 packages are handled across the 7 county post offices annually. Jewell County (county code JW) is a county located in the U.S. state of Kansas. As of the 2010 census, the county population was 3,077. Its county seat and most populous city is Mankato."