How many people live in Jefferson County, WI?
Updated Apr. 6, 2026Refreshed annually
In 2024, there were about 86,200 people living in Jefferson County, WI. That makes Jefferson County the 20th-most populous county in Wisconsin. It is home to 1.4% of people living in the state.
86.2K
population of Jefferson County, WI (2024)
1.4%
County share of the Wisconsin population (2024)
About 86,200 people lived in Jefferson County, WI in 2024.
Population estimates, 2000–2024
What are Jefferson County, WI’s age demographics?
About 17,100 Jefferson County, WI residents are aged 65 and older in 2024. That represents 19.8% of its population. For comparison, the age group represents 19.6% of Wisconsin’s population and 18% in the US overall.
Another 16,300 Jefferson County, WI residents, or 18.9% of the population, were children under 18. For comparison, the age group represents 20.8% of Wisconsin’s population and 21.6% in the US overall.
A lower share of Jefferson County, WI's population is aged 25–44 than the US as a whole.
Population estimates by age group, (2024)
What are Jefferson County, WI’s racial and ethnic demographics?
Non-Hispanic white residents make up 87.4% of the Jefferson County, WI population, higher than the national share of 57.5%.
In contrast, Jefferson County’s non-Hispanic Black or African American population accounts for 1.1%, below the 12.6% nationwide, and the Hispanic population makes up 8.8% of the county, compared with 20% nationally.
Racial and ethnic make up differ based on location. These figures reflect how people identified their race alone (not in combination with other races), and separate out Hispanic or Latino ethnicity, following Census reporting standards.
Jefferson County, WI has a higher share of a non-Hispanic white population than Wisconsin as a whole.
Population estimates by race and ethnicity, (2024)
The largest city or town in Jefferson County, WI is Watertown with about 14,500 residents in 2024.
Cities and towns in Jefferson County, WI ranked by population
Population (2024), includes only portions within county
| City or town | Population | |
|---|---|---|
| 1. | Watertown (pt.) | 14,461 |
| 2. | Fort Atkinson | 12,377 |
| 3. | Jefferson | 7,766 |
| 4. | Lake Mills | 6,617 |
| 5. | Ixonia | 5,067 |
| 6. | Whitewater (pt.) | 4,482 |
| 7. | Koshkonong | 3,769 |
| 8. | Waterloo | 3,611 |
| 9. | Johnson Creek | 3,398 |
| 10. | Oakland | 3,220 |
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Methodology
USAFacts standardizes data, in areas such as time and demographics, to make it easier to understand and compare.
The analysis was generated with the help of AI and reviewed by USAFacts for accuracy.
Page sources
USAFacts endeavors to share the most up-to-date information available. We sourced the data on this page directly from government agencies; however, the intervals at which agencies publish updated data vary.
