Where is Clinton County?

9 Clinton Counties in 9 states · 385,993 people (2025)

There are 9 counties named Clinton County in the United States, in Illinois, Indiana, Iowa, Kentucky, Michigan, Missouri, New York, Ohio and Pennsylvania. The most populous is Clinton County, Michigan (county seat: St. Johns), with 80,432 people in 2025. 7 of them are named after DeWitt Clinton, American politician (1769–1828).

All 9 Clinton Counties

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

State	County seat	Population 2025	Land area (sq mi)	Established	Named after
Clinton County, Illinois	Carlyle	37,128	474	1824	DeWitt Clinton
Clinton County, Indiana	Frankfort	33,322	405	1830	DeWitt Clinton
Clinton County, Iowa	Clinton	46,002	695	1837	DeWitt Clinton
Clinton County, Kentucky	Albany	9,139	197	1836	DeWitt Clinton
Clinton County, Michigan	St. Johns	80,432	567	1831	DeWitt Clinton
Clinton County, Missouri	Plattsburg	21,661	419	1833	DeWitt Clinton
Clinton County, New York	Plattsburgh	78,138	1,038	1788	George Clinton
Clinton County, Ohio	Wilmington	42,301	409	1810	George Clinton
Clinton County, Pennsylvania	Lock Haven	37,870	890	1839	DeWitt Clinton

Questions about Clinton Counties

How many Clinton Counties are there?

There are 9 Clinton Counties in the United States, in Illinois, Indiana, Iowa, Kentucky, Michigan, Missouri, New York, Ohio and Pennsylvania.

Which Clinton County is the largest?

By population, Clinton County, Michigan (80,432 people in 2025). By land area, Clinton County, New York (1,038 sq mi).

Which Clinton County is the oldest?

Clinton County, New York, established in 1788. The newest is Clinton County, Pennsylvania (1839).

Why are there so many Clinton Counties?

7 of the 9 are named after DeWitt Clinton, American politician (1769–1828). Many counties took their names from the same founders, presidents and generals as new states were organized.

How do I find out which Clinton 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.

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