County Maps US

Washington County, Illinois

A county in Illinois, ranked 75 of 102 by population.

CountyFIPS 17189

Within Illinois
Washington County, highlighted, with the areas around it. Boundaries generalised from the 2025 Census cartographic boundary file; neighbour fills carry no data. The dot marks Nashville, the county seat, located via the 2025 Census Gazetteer.

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Population
13,564
-165 (-1.2%) since 2020
Land area
562.6
square miles. A further 0.2% of the total area is water
Population density
24.1
people per square mile, computed rather than published
County seat
Nashville
Seat of county government.
Established
1818
207 years ago
Largest city
Nashville city
Population 3,011.

Sources: US Census Bureau, Population Estimates Program, Vintage 2025 Population Estimates, released 26 March 2026; US Census Bureau, Gazetteer Files, 2025 Gazetteer Files, released 10 September 2025; Wikidata (CC0), Wikidata. Retrieved 30 August 2026.

Satellite view

Aerial imagery of Washington County with its boundary drawn on top. A map shows you the shape; this shows you what is inside it, and which side of the line a place falls on.

Aerial view of Washington County, Illinois from the USGS National Map, with its boundary outlined
Imagery: USGS National Map, USGS Imagery Only, public domain, requested from USGS by your browser when you reach this point on the page, at 800 by 583 pixels. The boundary is the 2025 Census cartographic boundary file, reprojected to Web Mercator to match the imagery. You can also open the USGS National Map viewer.

Where Washington County ranks

Position among the 102 counties of Illinois, and among all 3,144 US counties and county-equivalents. Computed from the figures on this page.

MeasureValueIn IllinoisNationally
Population13,56475th of 1022,187th of 3,144
Land area562.6 sq mi44th of 1021,837th of 3,144
Population density24.1 per sq mi84th of 1022,090th of 3,144
Median household income$78,22420th of 102661st of 3,143

Full data for Washington County

Every figure below is attributed to the Census Bureau product it came from, with the vintage of that product.
MeasureValueSource and vintage
Population13,564Vintage 2025 Population Estimates
Population in 202013,729Vintage 2025 Population Estimates
2020 estimates base?13,765Vintage 2025 Population Estimates
Land area562.6 sq mi2025 Gazetteer Files
Water area1.3 sq mi2025 Gazetteer Files
Total area563.9 sq mi2025 Gazetteer Files
Population density?24.1 per sq miComputed: Vintage 2025 estimates divided by 2025 Gazetteer land area
Median household income$78,224American Community Survey 2020-2024 5-Year Estimates
Median home value$155,700American Community Survey 2020-2024 5-Year Estimates
Median age44.2American Community Survey 2020-2024 5-Year Estimates
Households5,795American Community Survey 2020-2024 5-Year Estimates
Housing units6,415American Community Survey 2020-2024 5-Year Estimates

Sources: US Census Bureau, Population Estimates Program, Vintage 2025 Population Estimates, released 26 March 2026; US Census Bureau, Gazetteer Files, 2025 Gazetteer Files, released 10 September 2025; US Census Bureau, American Community Survey, American Community Survey 2020-2024 5-Year Estimates, released 29 January 2026. Population density is computed here, not published: it divides the Vintage 2025 population estimate by the 2025 Gazetteer land area, which are two different Census products. Retrieved 30 August 2026.

How the population changed

The Census Bureau publishes the components behind an estimate, not just the total. For the year to July 2025:

Births minus deaths
-17
129 births, 146 deaths
Net migration
0
Arrivals and departures balanced.

Source: US Census Bureau, Population Estimates Program, Vintage 2025 Population Estimates, released 26 March 2026. Retrieved 30 August 2026.

The 6 areas bordering Washington County

Ordered by the length of the border actually shared, which the Census Bureau publishes in its county adjacency file and which no other county reference presents.

Bordering areaStateShared borderPopulation
Clinton CountyIllinois61 mi37,128
Perry CountyIllinois24 mi20,160
Jefferson CountyIllinois18 mi36,147
St. Clair CountyIllinois14 mi250,708
Randolph CountyIllinois6.0 mi29,921
Marion CountyIllinois2.0 mi36,382

Source: US Census Bureau, County Adjacency File, 2025 County Adjacency File, released 15 September 2025. Retrieved 30 August 2026.

All 102 counties of Illinois

Open the interactive Illinois county map, or jump straight to any of them.

Data on this page last rebuilt 30 August 2026. How these figures are produced.