Where is Richland County?

6 Richland Counties in 6 states · 620,212 people (2025)

There are 6 counties named Richland County in the United States, in Illinois, Montana, North Dakota, Ohio, South Carolina and Wisconsin. The most populous is Richland County, South Carolina (county seat: Columbia), with 434,956 people in 2025.

Map of the United States showing where all 6 Richland Counties are, labeled by state
Every Richland 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 6 Richland Counties

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

StateCounty seatPopulation 2025Land area (sq mi)EstablishedNamed after
Richland County, IllinoisOlney15,2193601841Richland County
Richland County, MontanaSidney11,3772,0851914–
Richland County, North DakotaWahpeton16,7311,4361873Morgan T. Rich
Richland County, OhioMansfield124,8934951808–
Richland County, South CarolinaColumbia434,9567571785–
Richland County, WisconsinRichland Center17,0365861842–

Questions about Richland Counties

How many Richland Counties are there?

There are 6 Richland Counties in the United States, in Illinois, Montana, North Dakota, Ohio, South Carolina and Wisconsin.

Which Richland County is the largest?

By population, Richland County, South Carolina (434,956 people in 2025). By land area, Richland County, Montana (2,085 sq mi).

Which Richland County is the oldest?

Richland County, South Carolina, established in 1785. The newest is Richland County, Montana (1914).

How do I find out which Richland 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