Washington County, Illinois
County seat: Nashville · Population 13,564 (2025) · 563 sq mi
Washington County is the 75th most populous of Illinois's 102 counties, with 13,564 people (2025 estimate). Its county seat is Nashville. It is part of the Southwest region, one of the 10 Illinois economic development regions (DCEO). The map shows its 14 cities and towns and the 6 neighboring counties.
Washington County facts
- County seat
- Nashville
- Population (2025 estimate)
- 13,564 −1.5% since 2020
- Land area
- 563 sq mi 44th largest of 102
- Water area
- 1 sq mi
- Population density
- 24 per sq mi
- Established
- 1818
- Same name
- One of 30 Washington Counties in the US
- Named after
- George Washington Founding Father and first U.S. president (1732–1799)
- Largest city
- Nashville 3,011
- Median household income
- $78,224
- Cities and towns
- 14
- ZIP codes
- 13
- Time zone
- Central
- FIPS code
- 17189
Cities and towns in Washington County
Washington County has 14 incorporated cities, towns and villages. Populations count the people living inside Washington County; cities that cross a county line also list the other counties.
| Name | Type | Population 2025 | Also in |
|---|---|---|---|
| Nashville (county seat) | City | 3,011 | |
| Okawville | Village | 1,343 | |
| Irvington | Village | 566 | |
| Hoyleton | Village | 502 | |
| Ashley | City | 449 | |
| Addieville | Village | 256 | |
| Richview | Village | 232 | |
| Oakdale | Village | 197 | |
| Radom | Village | 183 | |
| Du Bois | Village | 180 | |
| New Minden | Village | 166 | |
| Venedy | Village | 125 | |
| Wamac | City | 116 | Clinton and Marion counties |
| Centralia | City | 7 | Clinton, Jefferson and Marion counties |
ZIP codes in Washington County
13 ZIP codes reach into Washington County. ZIP codes ignore county lines, so some also cover a neighboring county.
- 62214
- 62237 also Perry and Randolph counties
- 62257 also St. Clair and Randolph counties
- 62263 also Perry County
- 62268 also Perry County
- 62271
- 62801 also Marion, Clinton and Jefferson counties
- 62803
- 62808 also Jefferson County
- 62831 also Perry County
- 62848
- 62876
- 62877 also Jefferson County
Population of Washington County, 2020–2025
Washington County shrank by 201 people (−1.5%) between April 2020 and July 2025: 157 more deaths than births and a net loss of 40 people from migration.
| Year (July 1) | Population |
|---|---|
| 2020 | 13,729 |
| 2021 | 13,654 |
| 2022 | 13,651 |
| 2023 | 13,574 |
| 2024 | 13,579 |
| 2025 | 13,564 |
Neighboring counties
- Clinton County north · 37,128 people
- Perry County south · 20,160 people
- Jefferson County east · 36,147 people
- St. Clair County west · 250,708 people
- Randolph County southwest · 29,921 people
- Marion County northeast · 36,382 people
Printable Washington 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) (97 KB)
- PNG (2400 px) (71 KB)
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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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