Karnes County is a county 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.GeographyAccording to the U.S. Census Bureau, the county has a total area of, of which is land and (0.8%) is water.Major highways25px U.S. Highway 18120px State Highway 7220px State Highway 8020px State Highway 12320px State Highway 239