County Maps US

Clay County, Illinois

A county in Illinois, ranked 80 of 102 by population.

CountyFIPS 17025

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

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Population
12,793
-478 (-3.6%) since 2020
Land area
468.4
square miles. A further 0.3% of the total area is water
Population density
27.3
people per square mile, computed rather than published
County seat
Louisville
Seat of county government.
Established
1824
201 years ago
Largest city
Flora city
Population 4,634.

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 Clay 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 Clay 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 730 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 Clay 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
Population12,79380th of 1022,233rd of 3,144
Land area468.4 sq mi59th of 1022,197th of 3,144
Population density27.3 per sq mi76th of 1022,007th of 3,144
Median household income$60,41783rd of 1022,049th of 3,143

Full data for Clay County

Every figure below is attributed to the Census Bureau product it came from, with the vintage of that product.
MeasureValueSource and vintage
Population12,793Vintage 2025 Population Estimates
Population in 202013,271Vintage 2025 Population Estimates
2020 estimates base?13,289Vintage 2025 Population Estimates
Land area468.4 sq mi2025 Gazetteer Files
Water area1.2 sq mi2025 Gazetteer Files
Total area469.5 sq mi2025 Gazetteer Files
Population density?27.3 per sq miComputed: Vintage 2025 estimates divided by 2025 Gazetteer land area
Median household income$60,417American Community Survey 2020-2024 5-Year Estimates
Median home value$97,400American Community Survey 2020-2024 5-Year Estimates
Median age40.4American Community Survey 2020-2024 5-Year Estimates
Households5,311American Community Survey 2020-2024 5-Year Estimates
Housing units6,165American 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
-36
140 births, 176 deaths
Net migration
-16
More people moved out than moved in.

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

The 6 areas bordering Clay 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
Richland CountyIllinois29 mi15,219
Wayne CountyIllinois24 mi15,882
Effingham CountyIllinois18 mi34,519
Marion CountyIllinois15 mi36,382
Jasper CountyIllinois9.6 mi9,032
Fayette CountyIllinois6.1 mi20,790

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.