There are 8 US Post Offices in Karnes County serving a total of 16,521 residents equating to 2,065 residents per post office. It's estimated that approximately 26,369 packages are handled across the 8 county post offices annually. Karnes County is a county located in the U.S. state of Texas. As of the 2010 census, the population was 14,824. Its county seat is Karnes City. The county is named for Henry Karnes, a soldier in the Texas Revolution. The former San Antonio and Aransas Pass Railway passed through Karnes County in its connection linking San Antonio with Corpus Christi."