County Maps US

Winnebago County, Illinois

A county in Illinois, ranked 7 of 102 by population.

CountyFIPS 17201

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

Download SVGFull Illinois map downloads

Population
283,674
-1,265 (-0.4%) since 2020
Land area
513
square miles. A further 1.2% of the total area is water
Population density
553
people per square mile, computed rather than published
County seat
Rockford
Seat of county government.
Established
1836
189 years ago
Largest city
Rockford city
Population 147,384 for the whole place, which extends beyond this county.

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 Winnebago 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 Winnebago 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 782 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 Winnebago 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
Population283,6747th of 102257th of 3,144
Land area513 sq mi51st of 1022,031st of 3,144
Population density553 per sq mi6th of 102260th of 3,144
Median household income$65,83759th of 1021,560th of 3,143

Full data for Winnebago County

Every figure below is attributed to the Census Bureau product it came from, with the vintage of that product.
MeasureValueSource and vintage
Population283,674Vintage 2025 Population Estimates
Population in 2020284,939Vintage 2025 Population Estimates
2020 estimates base?285,351Vintage 2025 Population Estimates
Land area513 sq mi2025 Gazetteer Files
Water area6.1 sq mi2025 Gazetteer Files
Total area519.2 sq mi2025 Gazetteer Files
Population density?553 per sq miComputed: Vintage 2025 estimates divided by 2025 Gazetteer land area
Median household income$65,837American Community Survey 2020-2024 5-Year Estimates
Median home value$164,500American Community Survey 2020-2024 5-Year Estimates
Median age39.6American Community Survey 2020-2024 5-Year Estimates
Households116,014American Community Survey 2020-2024 5-Year Estimates
Housing units125,002American 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
-65
3,064 births, 3,129 deaths
Net migration
+754
More people moved in than moved out.

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

The 6 areas bordering Winnebago 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
Ogle CountyIllinois27 mi51,399
Boone CountyIllinois24 mi53,568
Rock CountyWisconsin22 mi166,472
Stephenson CountyIllinois21 mi43,220
Green CountyWisconsin1.8 mi37,227
DeKalb CountyIllinoisa single point101,835

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.