Clark County, Illinois
County seat: Marshall · Population 15,114 (2025) · 501 sq mi
Clark County is the 71st most populous of Illinois's 102 counties, with 15,114 people (2025 estimate). Its county seat is Marshall. It is part of the Southeast region, one of the 10 Illinois economic development regions (DCEO). The map shows its 4 cities and towns and the 7 neighboring counties.
Clark County facts
- County seat
- Marshall
- Population (2025 estimate)
- 15,114 −2.4% since 2020
- Land area
- 501 sq mi 53rd largest of 102
- Water area
- 3 sq mi
- Population density
- 30 per sq mi
- Established
- 1819
- Same name
- One of 12 Clark Counties in the US
- Named after
- George Rogers Clark American surveyor, soldier, and militia officer (1752–1818)
- Largest city
- Marshall 3,880
- Median household income
- $72,927
- Cities and towns
- 4 plus 1 CDPs
- ZIP codes
- 11
- Time zone
- Central
- FIPS code
- 17023
Cities and towns in Clark County
Clark County has 4 incorporated cities, towns and villages. Populations count the people living inside Clark County; cities that cross a county line also list the other counties.
| Name | Type | Population 2025 | Also in |
|---|---|---|---|
| Marshall (county seat) | City | 3,880 | |
| Casey | City | 2,364 | Cumberland County |
| Martinsville | City | 1,083 | |
| Westfield | Village | 518 |
Unincorporated communities (CDPs)
Census-designated places are communities without their own city government; the county provides their services.
| Community | Population | Also in |
|---|---|---|
| West Union | 140 |
ZIP codes in Clark County
11 ZIP codes reach into Clark County. ZIP codes ignore county lines, so some also cover a neighboring county.
- 61933 also Edgar and Coles counties
- 61944 also Edgar County
- 62413 also Crawford County
- 62420 also Cumberland, Coles and Jasper counties
- 62423 also Edgar County
- 62441 also Edgar County
- 62442 also Crawford County
- 62449 also Crawford and Jasper counties
- 62474 also Coles County
- 62477
- 62478 also Crawford County
Population of Clark County, 2020–2025
Clark County shrank by 373 people (−2.4%) between April 2020 and July 2025: 368 more deaths than births and a net gain of 0 people from migration.
| Year (July 1) | Population |
|---|---|
| 2020 | 15,456 |
| 2021 | 15,384 |
| 2022 | 15,218 |
| 2023 | 15,235 |
| 2024 | 15,141 |
| 2025 | 15,114 |
Neighboring counties
- Edgar County north · 16,323 people
- Vigo County, Indiana east · 106,512 people
- Crawford County south · 18,648 people
- Cumberland County west · 10,208 people
- Sullivan County, Indiana southeast · 20,831 people
- Coles County northwest · 46,607 people
- Jasper County southwest · 9,032 people
Printable Clark County map
The PDF is a vector file with real text: it prints sharp on Letter paper and you can search it for a town. The PNG is 2400 pixels wide for slides and documents. Both are free to use with a credit to WhichCounty.
- PDF (Letter) (86 KB)
- PNG (2400 px) (69 KB)
Paste this code to embed the map on your site:
Sources
- Boundaries: U.S. Census Bureau, 2025 Cartographic Boundary Files (1:500,000).
- Population: Census Bureau county and city estimates, Vintage 2025. CDP populations: American Community Survey 2020–2024.
- Places and ZIP codes: Census Bureau 2026 Gazetteer and 2020 ZIP Code Tabulation Area relationship files.
- County seat, founding year and name origin: Wikidata (CC0), checked against state sources.
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