County Maps US

Fayette County, Illinois

A county in Illinois, ranked 55 of 102 by population.

CountyFIPS 17051

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

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Population
20,790
-693 (-3.2%) since 2020
Land area
716.5
square miles. A further 1.2% of the total area is water
Population density
29.0
people per square mile, computed rather than published
County seat
Vandalia
Seat of county government.
Established
1821
204 years ago
Largest city
Vandalia city
Population 7,108.

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 Fayette 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 Fayette 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 736 by 800 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 Fayette 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
Population20,79055th of 1021,787th of 3,144
Land area716.5 sq mi20th of 1021,263rd of 3,144
Population density29.0 per sq mi75th of 1021,954th of 3,144
Median household income$60,94479th of 1021,997th of 3,143

Full data for Fayette County

Every figure below is attributed to the Census Bureau product it came from, with the vintage of that product.
MeasureValueSource and vintage
Population20,790Vintage 2025 Population Estimates
Population in 202021,483Vintage 2025 Population Estimates
2020 estimates base?21,489Vintage 2025 Population Estimates
Land area716.5 sq mi2025 Gazetteer Files
Water area8.8 sq mi2025 Gazetteer Files
Total area725.3 sq mi2025 Gazetteer Files
Population density?29.0 per sq miComputed: Vintage 2025 estimates divided by 2025 Gazetteer land area
Median household income$60,944American Community Survey 2020-2024 5-Year Estimates
Median home value$130,700American Community Survey 2020-2024 5-Year Estimates
Median age41.9American Community Survey 2020-2024 5-Year Estimates
Households7,814American Community Survey 2020-2024 5-Year Estimates
Housing units8,808American 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
-71
205 births, 276 deaths
Net migration
-94
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 7 areas bordering Fayette 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
Marion CountyIllinois30 mi36,382
Effingham CountyIllinois27 mi34,519
Bond CountyIllinois20 mi16,959
Montgomery CountyIllinois19 mi28,076
Shelby CountyIllinois18 mi20,576
Clinton CountyIllinois6.3 mi37,128
Clay CountyIllinois6.1 mi12,793

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.