County Maps US

McDonough County, Illinois

A county in Illinois, ranked 51 of 102 by population.

CountyFIPS 17109

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

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Population
25,916
-1,212 (-4.5%) since 2020
Land area
589.3
square miles. A further 0.1% of the total area is water
Population density
44.0
people per square mile, computed rather than published
County seat
Macomb
Seat of county government.
Established
1826
199 years ago
Largest city
Macomb city
Population 14,530.

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 McDonough 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 McDonough 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 781 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 McDonough 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
Population25,91651st of 1021,589th of 3,144
Land area589.3 sq mi36th of 1021,662nd of 3,144
Population density44.0 per sq mi52nd of 1021,586th of 3,144
Median household income$52,79599th of 1022,611th of 3,143

Full data for McDonough County

Every figure below is attributed to the Census Bureau product it came from, with the vintage of that product.
MeasureValueSource and vintage
Population25,916Vintage 2025 Population Estimates
Population in 202027,128Vintage 2025 Population Estimates
2020 estimates base?27,254Vintage 2025 Population Estimates
Land area589.3 sq mi2025 Gazetteer Files
Water area0.80 sq mi2025 Gazetteer Files
Total area590.1 sq mi2025 Gazetteer Files
Population density?44.0 per sq miComputed: Vintage 2025 estimates divided by 2025 Gazetteer land area
Median household income$52,795American Community Survey 2020-2024 5-Year Estimates
Median home value$107,500American Community Survey 2020-2024 5-Year Estimates
Median age34.9American Community Survey 2020-2024 5-Year Estimates
Households11,856American Community Survey 2020-2024 5-Year Estimates
Housing units13,587American 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
-106
236 births, 342 deaths
Net migration
-92
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 McDonough 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
Hancock CountyIllinois24 mi16,803
Schuyler CountyIllinois24 mi6,657
Fulton CountyIllinois24 mi32,901
Warren CountyIllinois18 mi16,222
Henderson CountyIllinois6.0 mi5,984

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.