COUNTY · IN
Decatur County, Indiana
Decatur County is a county in Indiana with FIPS code 18031 and an estimated population of 26,399 (Census 2023), 60th largest of 92 in the state.
County facts
- Name
- Decatur County
- State
- Indiana
- Type
- county
- FIPS code
- 18031
- State FIPS
- 18
- Population (2023)
- 26,399
- Change since 2020
- -0.3%
- State rank
- 60 of 92
Population is the Census Bureau’s Vintage 2023 estimate.
Questions
What is the FIPS code for Decatur County?
Decatur County, Indiana has the five-digit FIPS code 18031: 18 for the state and 031 for the county.
What state is Decatur County in?
Decatur County is in Indiana.
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.