Where is Sioux County?

3 Sioux Counties in 3 states · 41,629 people (2025)

There are 3 counties named Sioux County in the United States, in Iowa, Nebraska and North Dakota. The most populous is Sioux County, Iowa (county seat: Orange City), with 36,774 people in 2025. 3 of them are named after Sioux, Native American and First Nations ethnic group.

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

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

StateCounty seatPopulation 2025Land area (sq mi)EstablishedNamed after
Sioux County, IowaOrange City36,7747681851Sioux
Sioux County, NebraskaHarrison1,1882,0671877Sioux
Sioux County, North DakotaFort Yates3,6671,0941915Sioux

Questions about Sioux Counties

How many Sioux Counties are there?

There are 3 Sioux Counties in the United States, in Iowa, Nebraska and North Dakota.

Which Sioux County is the largest?

By population, Sioux County, Iowa (36,774 people in 2025). By land area, Sioux County, Nebraska (2,067 sq mi).

Which Sioux County is the oldest?

Sioux County, Iowa, established in 1851. The newest is Sioux County, North Dakota (1915).

Why are there so many Sioux Counties?

3 of the 3 are named after Sioux, Native American and First Nations ethnic group. Many counties took their names from the same founders, presidents and generals as new states were organized.

How do I find out which Sioux 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