COUNTY · WI
Jefferson County, Wisconsin
Jefferson County is a county in Wisconsin with FIPS code 55055 and an estimated population of 85,743 (Census 2023), 20th largest of 72 in the state.
County facts
- Name
- Jefferson County
- State
- Wisconsin
- Type
- county
- FIPS code
- 55055
- State FIPS
- 55
- Population (2023)
- 85,743
- Change since 2020
- -0.5%
- State rank
- 20 of 72
Population is the Census Bureau’s Vintage 2023 estimate.
Questions
What is the FIPS code for Jefferson County?
Jefferson County, Wisconsin has the five-digit FIPS code 55055: 55 for the state and 055 for the county.
What state is Jefferson County in?
Jefferson County is in Wisconsin.
How do I know if an address is in this county?
Use the address lookup. ZIP codes and city names can cross county lines, so an address is the reliable check.
Sources: U.S. Census Bureau geographic reference files; Census Bureau Population Estimates, Vintage 2023. Last reviewed 2026-10-27.