Where is Hamilton County?

10 Hamilton Counties in 10 states · 1.7 million people (2025)

There are 10 counties named Hamilton County in the United States, in Florida, Illinois, Indiana, Iowa, Kansas, Nebraska, New York, Ohio, Tennessee and Texas. The most populous is Hamilton County, Ohio (county seat: Cincinnati), with 838,418 people in 2025. 8 of them are named after Alexander Hamilton, American Founding Father and statesman (1755/1757–1804).

Map of the United States showing where all 10 Hamilton Counties are, labeled by state
Every Hamilton 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 10 Hamilton Counties

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

StateCounty seatPopulation 2025Land area (sq mi)EstablishedNamed after
Hamilton County, FloridaJasper14,1805141827Alexander Hamilton
Hamilton County, IllinoisMcLeansboro7,8594351821Alexander Hamilton
Hamilton County, IndianaNoblesville387,0363941823Alexander Hamilton
Hamilton County, IowaWebster City14,9445771856William W. Hamilton
Hamilton County, KansasSyracuse2,5009971873Alexander Hamilton
Hamilton County, NebraskaAurora9,6785421867Alexander Hamilton
Hamilton County, New YorkLake Pleasant5,0061,7171816Alexander Hamilton
Hamilton County, OhioCincinnati838,4184061790Alexander Hamilton
Hamilton County, TennesseeChattanooga390,8335421819Alexander Hamilton
Hamilton County, TexasHamilton8,6808361856James Hamilton

Questions about Hamilton Counties

How many Hamilton Counties are there?

There are 10 Hamilton Counties in the United States, in Florida, Illinois, Indiana, Iowa, Kansas, Nebraska, New York, Ohio, Tennessee and Texas.

Which Hamilton County is the largest?

By population, Hamilton County, Ohio (838,418 people in 2025). By land area, Hamilton County, New York (1,717 sq mi).

Which Hamilton County is the oldest?

Hamilton County, Ohio, established in 1790. The newest is Hamilton County, Kansas (1873).

Why are there so many Hamilton Counties?

8 of the 10 are named after Alexander Hamilton, American Founding Father and statesman (1755/1757–1804). Many counties took their names from the same founders, presidents and generals as new states were organized.

How do I find out which Hamilton 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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Other common county names