County Maps US

Stephenson County, Illinois

A county in Illinois, ranked 33 of 102 by population.

CountyFIPS 17177

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

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Population
43,220
-1,350 (-3.0%) since 2020
Land area
564.2
square miles. A further 0.1% of the total area is water
Population density
76.6
people per square mile, computed rather than published
County seat
Freeport
Seat of county government.
Established
1837
188 years ago
Largest city
Freeport city
Population 23,202.

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 Stephenson 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 Stephenson 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 649 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 Stephenson 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
Population43,22033rd of 1021,132nd of 3,144
Land area564.2 sq mi43rd of 1021,821st of 3,144
Population density76.6 per sq mi31st of 1021,112th of 3,144
Median household income$64,04364th of 1021,701st of 3,143

Full data for Stephenson County

Every figure below is attributed to the Census Bureau product it came from, with the vintage of that product.
MeasureValueSource and vintage
Population43,220Vintage 2025 Population Estimates
Population in 202044,570Vintage 2025 Population Estimates
2020 estimates base?44,696Vintage 2025 Population Estimates
Land area564.2 sq mi2025 Gazetteer Files
Water area0.52 sq mi2025 Gazetteer Files
Total area564.8 sq mi2025 Gazetteer Files
Population density?76.6 per sq miComputed: Vintage 2025 estimates divided by 2025 Gazetteer land area
Median household income$64,043American Community Survey 2020-2024 5-Year Estimates
Median home value$134,900American Community Survey 2020-2024 5-Year Estimates
Median age45.3American Community Survey 2020-2024 5-Year Estimates
Households19,358American Community Survey 2020-2024 5-Year Estimates
Housing units21,330American 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
-210
416 births, 626 deaths
Net migration
+6
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 Stephenson 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
Green CountyWisconsin22 mi37,227
Jo Daviess CountyIllinois21 mi21,594
Winnebago CountyIllinois21 mi283,674
Ogle CountyIllinois15 mi51,399
Carroll CountyIllinois12 mi15,419
Lafayette CountyWisconsin4.5 mi17,478

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.