Where is Clark County?

12 Clark Counties in 12 states · 3.3 million people (2025)

There are 12 counties named Clark County in the United States, in Arkansas, Idaho, Illinois, Indiana, Kansas, Kentucky, Missouri, Nevada, Ohio, South Dakota, Washington and Wisconsin. The most populous is Clark County, Nevada (county seat: Las Vegas), with 2,407,226 people in 2025. 5 of them are named after George Rogers Clark, American surveyor, soldier, and militia officer (1752–1818).

Map of the United States showing where all 12 Clark Counties are, labeled by state
Every Clark County in the United States (red), labeled with its state. Boundaries: U.S. Census Bureau, 2025. Free to use with attribution (CC BY 4.0).

All 12 Clark Counties

Sorted by state. Each link opens the county's map.

StateCounty seatPopulation 2025Land area (sq mi)EstablishedNamed after
Clark County, ArkansasArkadelphia20,9388661818William Clark
Clark County, IdahoDubois7831,7631919Sam K. Clark
Clark County, IllinoisMarshall15,1145011819George Rogers Clark
Clark County, IndianaJeffersonville130,4513731801George Rogers Clark
Clark County, KansasAshland1,9009751885Charles F. Clarke
Clark County, KentuckyWinchester37,8882531792George Rogers Clark
Clark County, MissouriKahoka6,4755051836William Clark
Clark County, NevadaLas Vegas2,407,2267,8921909William A. Clark
Clark County, OhioSpringfield135,3403961818George Rogers Clark
Clark County, South DakotaClark4,0319581873Newton Clark
Clark County, WashingtonVancouver532,1196291845William Clark
Clark County, WisconsinNeillsville35,0521,2101853George Rogers Clark

Questions about Clark Counties

How many Clark Counties are there?

There are 12 Clark Counties in the United States, in Arkansas, Idaho, Illinois, Indiana, Kansas, Kentucky, Missouri, Nevada, Ohio, South Dakota, Washington and Wisconsin.

Which Clark County is the largest?

By population, Clark County, Nevada (2,407,226 people in 2025). By land area, Clark County, Nevada (7,892 sq mi).

Which Clark County is the oldest?

Clark County, Kentucky, established in 1792. The newest is Clark County, Idaho (1919).

Why are there so many Clark Counties?

5 of the 12 are named after George Rogers Clark, American surveyor, soldier, and militia officer (1752–1818). Many counties took their names from the same founders, presidents and generals as new states were organized.

How do I find out which Clark County an address is in?

Open the county map of the state: it has a search box for cities, towns and ZIP codes. On a phone, the "what county am I in" tool on our sister site uses your location.

What county am I in? →

Other common county names