There are 6 US Post Offices in Neosho County serving a total of 16,498 residents equating to 2,750 residents per post office. It's estimated that approximately 26,333 packages are handled across the 6 county post offices annually. Neosho County (standard abbreviation: NO) is a county located in the south east of the U.S. state of Kansas. As of the 2010 census, the county population was 16,512. The county seat is Erie."