There are 2 US Post Offices in Seward County serving a total of 22,808 residents equating to 11,404 residents per post office. It's estimated that approximately 36,404 packages are handled across the 2 county post offices annually. Seward County (standard abbreviation: SW) is a county of the U.S. state of Kansas. As of the 2010 census, the county population was 22,952. The largest city and county seat is Liberal. The county was formed on March 20, 1873 and named after William Henry Seward, an American politician and Secretary of State under Abraham Lincoln and Andrew Johnson."