County Maps US

Jefferson County, Wisconsin

A county in Wisconsin, ranked 20 of 72 by population.

CountyFIPS 55055

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

Download SVGFull Wisconsin map downloads

Population
86,505
+286 (+0.3%) since 2020
Land area
556.5
square miles. A further 4.5% of the total area is water
Population density
155
people per square mile, computed rather than published
County seat
Jefferson
Seat of county government.
Established
1836
189 years ago
Largest city
Watertown city
Population 14,485 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 Jefferson 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 Jefferson County, Wisconsin 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 787 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 Jefferson County ranks

Position among the 72 counties of Wisconsin, and among all 3,144 US counties and county-equivalents. Computed from the figures on this page.

MeasureValueIn WisconsinNationally
Population86,50520th of 72687th of 3,144
Land area556.5 sq mi53rd of 721,863rd of 3,144
Population density155 per sq mi17th of 72682nd of 3,144
Median household income$83,75010th of 72457th of 3,143

Full data for Jefferson County

Every figure below is attributed to the Census Bureau product it came from, with the vintage of that product.
MeasureValueSource and vintage
Population86,505Vintage 2025 Population Estimates
Population in 202086,219Vintage 2025 Population Estimates
2020 estimates base?86,171Vintage 2025 Population Estimates
Land area556.5 sq mi2025 Gazetteer Files
Water area26.2 sq mi2025 Gazetteer Files
Total area582.7 sq mi2025 Gazetteer Files
Population density?155 per sq miComputed: Vintage 2025 estimates divided by 2025 Gazetteer land area
Median household income$83,750American Community Survey 2020-2024 5-Year Estimates
Median home value$274,100American Community Survey 2020-2024 5-Year Estimates
Median age41.5American Community Survey 2020-2024 5-Year Estimates
Households34,873American Community Survey 2020-2024 5-Year Estimates
Housing units36,890American 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
+8
816 births, 808 deaths
Net migration
-48
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 Jefferson 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
Waukesha CountyWisconsin24 mi417,210
Dane CountyWisconsin24 mi590,375
Dodge CountyWisconsin24 mi89,097
Rock CountyWisconsin12 mi166,472
Walworth CountyWisconsin12 mi106,127

Source: US Census Bureau, County Adjacency File, 2025 County Adjacency File, released 15 September 2025. Retrieved 30 August 2026.

All 72 counties of Wisconsin

Open the interactive Wisconsin county map, or jump straight to any of them.

Data on this page last rebuilt 30 August 2026. How these figures are produced.