COUNTY · IA
Jefferson County, Iowa
Jefferson County is a county in Iowa with FIPS code 19101 and an estimated population of 15,440 (Census 2023), 48th largest of 99 in the state.
County facts
- Name
- Jefferson County
- State
- Iowa
- Type
- county
- FIPS code
- 19101
- State FIPS
- 19
- Population (2023)
- 15,440
- Change since 2020
- -1.6%
- State rank
- 48 of 99
Population is the Census Bureau’s Vintage 2023 estimate.
Questions
What is the FIPS code for Jefferson County?
Jefferson County, Iowa has the five-digit FIPS code 19101: 19 for the state and 101 for the county.
What state is Jefferson County in?
Jefferson County is in Iowa.
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.