COUNTY · CO
Jefferson County, Colorado
Jefferson County is a county in Colorado with FIPS code 08059 and an estimated population of 576,366 (Census 2023), 4th largest of 64 in the state.
County facts
- Name
- Jefferson County
- State
- Colorado
- Type
- county
- FIPS code
- 08059
- State FIPS
- 08
- Population (2023)
- 576,366
- Change since 2020
- -1.2%
- State rank
- 4 of 64
Population is the Census Bureau’s Vintage 2023 estimate.
Questions
What is the FIPS code for Jefferson County?
Jefferson County, Colorado has the five-digit FIPS code 08059: 08 for the state and 059 for the county.
What state is Jefferson County in?
Jefferson County is in Colorado.
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.