Where is Oneida County?

3 Oneida Counties in 3 states · 269,608 people (2025)

There are 3 counties named Oneida County in the United States, in Idaho, New York and Wisconsin. The most populous is Oneida County, New York (county seat: Utica), with 226,392 people in 2025. 2 of them are named after Oneida, ethnic group in North America.

Map of the United States showing where all 3 Oneida Counties are, labeled by state
Every Oneida 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 3 Oneida Counties

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

StateCounty seatPopulation 2025Land area (sq mi)EstablishedNamed after
Oneida County, IdahoMalad City5,0851,1991864Oneida Lake
Oneida County, New YorkUtica226,3921,2121798Oneida
Oneida County, WisconsinRhinelander38,1311,1141887Oneida

Questions about Oneida Counties

How many Oneida Counties are there?

There are 3 Oneida Counties in the United States, in Idaho, New York and Wisconsin.

Which Oneida County is the largest?

By population, Oneida County, New York (226,392 people in 2025). By land area, Oneida County, New York (1,212 sq mi).

Which Oneida County is the oldest?

Oneida County, New York, established in 1798. The newest is Oneida County, Wisconsin (1887).

Why are there so many Oneida Counties?

2 of the 3 are named after Oneida, ethnic group in North America. Many counties took their names from the same founders, presidents and generals as new states were organized.

How do I find out which Oneida 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