Where is Lake County?

12 Lake Counties in 12 states · 2.1 million people (2025)

There are 12 counties named Lake County in the United States, in California, Colorado, Florida, Illinois, Indiana, Michigan, Minnesota, Montana, Ohio, Oregon, South Dakota and Tennessee. The most populous is Lake County, Illinois (county seat: Waukegan), with 719,339 people in 2025. 3 of them are named after lake, body of relatively still water, localized in a basin.

Map of the United States showing where all 12 Lake Counties are, labeled by state
Every Lake 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 Lake Counties

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

StateCounty seatPopulation 2025Land area (sq mi)EstablishedNamed after
Lake County, CaliforniaLakeport67,7721,2551861Clear Lake
Lake County, ColoradoLeadville7,5523771861Twin Lakes
Lake County, FloridaTavares456,0689541887lake
Lake County, IllinoisWaukegan719,3394441839Lake Michigan
Lake County, IndianaCrown Point504,6124991837Lake Michigan
Lake County, MichiganBaldwin13,1825681840lake
Lake County, MinnesotaTwo Harbors10,7462,1091856Lake Superior
Lake County, MontanaPolson33,3921,4911923Flathead Lake
Lake County, OhioPainesville232,2172291840Lake Erie
Lake County, OregonLakeview8,1878,1391874lake
Lake County, South DakotaMadison10,9935631873–
Lake County, TennesseeTiptonville6,2491661870Reelfoot Lake

Questions about Lake Counties

How many Lake Counties are there?

There are 12 Lake Counties in the United States, in California, Colorado, Florida, Illinois, Indiana, Michigan, Minnesota, Montana, Ohio, Oregon, South Dakota and Tennessee.

Which Lake County is the largest?

By population, Lake County, Illinois (719,339 people in 2025). By land area, Lake County, Oregon (8,139 sq mi).

Which Lake County is the oldest?

Lake County, Indiana, established in 1837. The newest is Lake County, Montana (1923).

Why are there so many Lake Counties?

3 of the 12 are named after lake, body of relatively still water, localized in a basin. Many counties took their names from the same founders, presidents and generals as new states were organized.

How do I find out which Lake 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