Census-designated place · Wisconsin
Lake Koshkonong, Wisconsin
Lake Koshkonong, census-designated place, in Jefferson County, Wisconsin. Lake Koshkonong had 1,239 residents in the 2020 Census, a full count; the ACS 2020-2024 5-year estimates put it at 1,010 (±157). GEOID 5541583.
Residents, 2020 Census
1,239
Census count or controlled total
ACS 2020-2024 estimate: 1,010 ±157
Median household income
$97,115
±$3,504 (90% margin)
Wisconsin: $77,485
Median home value
$370,300
±$26,911 (90% margin)
Wisconsin: $266,500
Median gross rent
$1,296
±$160 (90% margin)
Wisconsin: $1,087
Where is Lake Koshkonong and what county is it in?
Lake Koshkonong is a census-designated place: an unincorporated community the Census Bureau draws for counting, with no city government of its own, in Jefferson County, Wisconsin. It covers 14.1 square miles of land, 88 residents per square mile in 2020.
Lake Koshkonong is in the Watertown-Fort Atkinson, WI micropolitan statistical area (Census Bureau delineation, July 2023).
Lake Koshkonong lies mostly within the Town of Koshkonong and reaches into the Town of Sumner (Jefferson County), towns or townships with their own local government (2020 census blocks).
Source: 2024 Gazetteer and 2020 place-by-county files, U.S. Census Bureau · Census reference files
How many people live in Lake Koshkonong, and is it growing?
The 2020 Census counted 1,239 residents in Lake Koshkonong, a full count rather than a sample. The 2020-2024 American Community Survey, a sample, estimates 1,010 (±157).
The Census Bureau publishes yearly population estimates for incorporated places only; Lake Koshkonong is a census-designated place, so its figures come from the ACS and the 2020 Census.
| Measure | Lake Koshkonong | Jefferson County | Change since 2015-2019 |
|---|---|---|---|
| Total population | 1,010 ±157 | 86,003 | no clear change |
| Households | 498 ±76 | 34,873 | no clear change |
| Average household size | 2.03 ±0.19 | 2.37 | no clear change |
| Housing units | 731 ±83 | 36,890 | no clear change |
Source: American Community Survey 2020-2024 5-year estimates, U.S. Census Bureau (released January 2026); Census PEP Vintage 2025 (SUB-EST2025, CO-EST2025); 2020 Census P.L. 94-171 · Check it at data.census.gov
Who lives in Lake Koshkonong?
The median resident of Lake Koshkonong is 54.0 years old; 15.3% are under 18 and 31.5% are 65 or older. The largest group is non-Hispanic white residents at 93.8%, then Hispanic or Latino residents (of any race) at 2.8%.
| Measure | Lake Koshkonong | Jefferson County | Change since 2015-2019 |
|---|---|---|---|
| Median age | 54.0 ±6.0 | 41.5 | no clear change |
| Under 18 years | 15.3% ±5.3 pts | 19.7% | – |
| 65 years and over | 31.5% ±6.0 pts | 18.5% | – |
| Male | 53.7% ±4.5 pts | 50.0% | – |
| Hispanic or Latino (any race) | 2.8% ±3.9 pts | 8.5% | – |
| White alone, not Hispanic | 93.8% ±4.4 pts | 87.0% | no clear change |
| Black or African American alone, not Hispanic | 0.9% ±1.5 pts | 0.9% | – |
| Asian alone, not Hispanic | 0.5% ±0.6 pts | 0.6% | – |
| American Indian and Alaska Native alone, not Hispanic | 0.0% ±2.2 pts | 0.1% | – |
| Native Hawaiian and Other Pacific Islander alone, not Hispanic | 0.0% ±2.2 pts | 0.0% | – |
| Two or more races, not Hispanic | 1.7% ±1.6 pts | 2.7% | – |
| Some other race alone, not Hispanic | 0.4% ±0.8 pts | 0.3% | – |
| Born outside the United States | 0.6% ±0.7 pts | 3.7% | – |
| Speak a language other than English at home (age 5+) | 0.9% ±1.1 pts | 6.3% | – |
| Civilian veterans (age 18+) | 9.4% ±3.4 pts | 6.4% | – |
| With a disability | 14.7% ±5.2 pts | 12.8% | – |
| No health insurance coverage | 3.6% ±4.1 pts | 4.8% | – |
| High school graduate or higher (age 25+) | 97.0% ±2.3 pts | 92.9% | – |
| Bachelor's degree or higher (age 25+) | 27.2% ±6.7 pts | 28.5% | no clear change |
| Graduate or professional degree (age 25+) | 9.3% ±4.1 pts | 8.9% | – |
| Lived in the same house a year earlier | 90.1% ±6.1 pts | 90.3% | – |
| Moved from another state in the past year | 1.9% ±2.3 pts | 1.2% | – |
Source: American Community Survey 2020-2024 5-year estimates, U.S. Census Bureau (released January 2026) (Data Profiles DP02, DP05) · Check it at data.census.gov
What do households in Lake Koshkonong earn?
Half of Lake Koshkonong's 498 households earn less than $97,115 a year (±$3,504), against $83,750 in Jefferson County and $77,485 in Wisconsin. In 2015-2019 it was $93,401 in 2024 dollars; the margins of error cannot tell the two periods apart. 5.8% of residents live below the poverty line.
| Measure | Lake Koshkonong | Jefferson County | Change since 2015-2019 |
|---|---|---|---|
| Median household income | $97,115 ±$3,504 | $83,750 | no clear change |
| Mean household income | $127,564 ±$20,818 | $100,082 | – |
| Per capita income | $61,161 ±$10,133 | $41,881 | no clear change |
| People below the poverty line | 5.8% ±3.2 pts | 8.1% | no clear change |
| Children under 18 below the poverty line | 5.2% ±9.1 pts | 9.8% | – |
| Households receiving SNAP | 0.6% ±0.9 pts | 9.2% | – |
| Households with a computer | 94.4% ±3.0 pts | 94.6% | – |
| Households with a broadband subscription | 92.8% ±3.6 pts | 90.6% | – |
Source: American Community Survey 2020-2024 5-year estimates, U.S. Census Bureau (released January 2026) (Data Profile DP03) · Check it at data.census.gov
What does housing cost in Lake Koshkonong?
Owners occupy 90.4% of Lake Koshkonong's occupied homes and renters 9.6%. The median owner-occupied home is valued at $370,300 by its owner (±$26,911). The median renter pays $1,296 a month including utilities.
| Measure | Lake Koshkonong | Jefferson County | Change since 2015-2019 |
|---|---|---|---|
| Median home value (owner-occupied) | $370,300 ±$26,911 | $274,100 | +$44,412 |
| Median gross rent | $1,296 ±$160 | $1,035 | no clear change |
| Renters paying 35% or more of income on rent | 54.8% ±36.3 pts | 30.0% | – |
| Median monthly owner costs, with a mortgage | $2,061 ±$348 | $1,730 | – |
| Owner-occupied homes | 90.4% ±5.9 pts | 73.1% | no clear change |
| Renter-occupied homes | 9.6% ±5.9 pts | 26.9% | – |
| Housing units | 731 ±83 | 36,890 | no clear change |
| Homeowner vacancy rate | 1.1% ±1.8 pts | 0.2% | – |
| Rental vacancy rate | 0.0% ±35.3 pts | 4.5% | – |
| Single-family detached homes | 96.4% ±1.8 pts | 71.6% | – |
| Mobile homes | 0.0% ±3.0 pts | 3.6% | – |
| Built 2020 or later | 1.2% ±1.3 pts | 1.1% | – |
| Built 2010 to 2019 | 9.0% ±4.0 pts | 5.4% | – |
| Built 1939 or earlier | 19.4% ±7.5 pts | 24.3% | – |
| Households with no vehicle | 1.2% ±1.9 pts | 4.6% | – |
Source: American Community Survey 2020-2024 5-year estimates, U.S. Census Bureau (released January 2026) (Data Profile DP04) · Check it at data.census.gov
How do people in Lake Koshkonong work and get to work?
79.3% of Lake Koshkonong's workers drive alone and 12.9% work from home. The average trip to work takes 25.6 minutes.
| Measure | Lake Koshkonong | Jefferson County | Change since 2015-2019 |
|---|---|---|---|
| In the labor force (age 16+) | 63.4% ±7.7 pts | 68.3% | – |
| Unemployment rate | 1.2% ±1.4 pts | 3.6% | – |
| Drove alone to work | 79.3% ±7.5 pts | 76.9% | – |
| Carpooled | 7.9% ±5.6 pts | 8.1% | – |
| Public transportation | 0.0% ±4.1 pts | 0.4% | – |
| Walked | 0.0% ±4.1 pts | 3.0% | – |
| Worked from home | 12.9% ±5.3 pts | 10.5% | +8.3 pts |
| Mean travel time to work | 25.6 min ±3.0 | 24.8 min | −5.6 min |
Source: American Community Survey 2020-2024 5-year estimates, U.S. Census Bureau (released January 2026) (Data Profile DP03) · Check it at data.census.gov
What census tracts are in Lake Koshkonong?
No census tract lies mostly in Lake Koshkonong; 1 tract reaches into it (2020 census blocks).
| Tract | Residents, 2020-2024 | Median household income |
|---|---|---|
| Tract 1012.01Jefferson County | 2,123 | $98,456 |
Source: American Community Survey 2020-2024 5-year estimates, U.S. Census Bureau (released January 2026); 2020 block assignment files (tract share = share of the tract's census blocks in Lake Koshkonong) · Census block assignment files
How does Lake Koshkonong compare with other places in Wisconsin?
Lake Koshkonong ranks 279th of 914 places in Wisconsin with 1,000 or more residents and a reliable estimate, by median household income.
| Measure | Rank | Of |
|---|---|---|
| Population (ACS 2020-2024) | 867th | 914 |
| Residents per square mile | 495th | 914 |
| Median household income | 279th | 914 |
| Per capita income | 63rd | 911 |
| Median home value | 164th | 913 |
| Median gross rent | 137th | 825 |
| Poverty rate | 451st | 706 |
| Bachelor's degree or higher | 443rd | 914 |
| Median age | 103rd | 914 |
| Owner-occupied share | 296th | 914 |
| Work from home | 334th | 827 |
| Travel time to work | 326th | 914 |
Lake Koshkonong's figures with every place in Wisconsin (CSV)
Every place in Wisconsin, sortable · Compare Lake Koshkonong with other places
Source: PlainCities ranks computed from the American Community Survey 2020-2024 5-year estimates, U.S. Census Bureau (released January 2026) and PEP Vintage 2025 · How ranks are computed
How reliable are the figures for Lake Koshkonong?
23 of the 57 figures for Lake Koshkonong on this page carry a coefficient of variation over 40% and are marked with a ring: they come from a small sample, so read them as rough.
The American Community Survey samples about one household in eight over five years, so every figure is an estimate with a 90% margin of error (shown under each value). A ring marks an estimate whose coefficient of variation is over 40%. A change is called only when the gap between the two periods is larger than their combined 90% margin (the square root of the sum of the two squared margins), the Census Bureau's test. How to read a margin of error.
Source: American Community Survey 2020-2024 5-year estimates, U.S. Census Bureau (released January 2026): margins of error as published · ACS technical documentation
How these figures are made: methodology and release checks · reading a margin of error · every state · corrections
Not on this page: crime, weather and schools for Lake Koshkonong are other agencies' records. Crime: the FBI's Crime Data Explorer · climate: NOAA's U.S. Climate Normals · schools: the National Center for Education Statistics' school search.