There are 2 US Post Offices in Kearny County serving a total of 3,860 residents equating to 1,930 residents per post office. It's estimated that approximately 6,161 packages are handled across the 2 county post offices annually. Kearny County (county code KE) is a county located in the U.S. state of Kansas. As of the 2010 census, the county population was 3,977. Its county seat and most populous city is Lakin. The county is named in honor of General Philip Kearny."