County Maps US

Brown County, Illinois

A county in Illinois, ranked 91 of 102 by population.

CountyFIPS 17009

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

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Population
6,401
+169 (+2.7%) since 2020
Land area
305.7
square miles. A further 0.5% of the total area is water
Population density
20.9
people per square mile, computed rather than published
County seat
Mount Sterling
Seat of county government.
Established
1839
186 years ago
Largest city
Mount Sterling city
Population 2,155.

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 Brown 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 Brown 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 698 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 Brown 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
Population6,40191st of 1022,706th of 3,144
Land area305.7 sq mi91st of 1022,797th of 3,144
Population density20.9 per sq mi89th of 1022,213th of 3,144
Median household income$67,91747th of 1021,346th of 3,143

Full data for Brown County

Every figure below is attributed to the Census Bureau product it came from, with the vintage of that product.
MeasureValueSource and vintage
Population6,401Vintage 2025 Population Estimates
Population in 20206,232Vintage 2025 Population Estimates
2020 estimates base?6,245Vintage 2025 Population Estimates
Land area305.7 sq mi2025 Gazetteer Files
Water area1.6 sq mi2025 Gazetteer Files
Total area307.3 sq mi2025 Gazetteer Files
Population density?20.9 per sq miComputed: Vintage 2025 estimates divided by 2025 Gazetteer land area
Median household income$67,917American Community Survey 2020-2024 5-Year Estimates
Median home value$150,300American Community Survey 2020-2024 5-Year Estimates
Median age41.0American Community Survey 2020-2024 5-Year Estimates
Households2,041American Community Survey 2020-2024 5-Year Estimates
Housing units2,321American 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
-7
48 births, 55 deaths
Net migration
-28
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 5 areas bordering Brown 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
Schuyler CountyIllinois35 mi6,657
Pike CountyIllinois18 mi14,231
Adams CountyIllinois18 mi64,267
Cass CountyIllinois9.2 mi12,463
Morgan CountyIllinois2.8 mi32,515

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.