There are 8 US Post Offices in Greenwood County serving a total of 7,146 residents equating to 893 residents per post office. It's estimated that approximately 11,406 packages are handled across the 8 county post offices annually. Greenwood County (county code GW) is a county located in the southeast portion of the U.S. state of Kansas. As of the 2010 census, the county population was 6,689. Its county seat and most populous city is Eureka."