Clark County is the name of twelve counties in the United States. Most, though not all, are named after two brothers: military hero George Rogers Clark in the Midwest, and explorer William Clark in the West. Clark County, Arkansas Clark County, Idaho Clark County, Illinois Clark County, Indiana Clark County, Kansas Clark County, Kentucky Clark County, Missouri Clark County, Nevada, the most populous county bearing the name Clark, containing Las Vegas Clark County, Ohio Clark County, South Dakota Clark County, Washington Clark County, Wisconsin See also Clarke County (disambiguation) Lewis and Clark County, Montana