COUNTY · KY
Allen County, Kentucky
Allen County is a county in Kentucky with FIPS code 21003 and an estimated population of 21,788 (Census 2023), 53rd largest of 120 in the state.
County facts
- Name
- Allen County
- State
- Kentucky
- Type
- county
- FIPS code
- 21003
- State FIPS
- 21
- Population (2023)
- 21,788
- Change since 2020
- +5.9%
- State rank
- 53 of 120
Population is the Census Bureau’s Vintage 2023 estimate.
Questions
What is the FIPS code for Allen County?
Allen County, Kentucky has the five-digit FIPS code 21003: 21 for the state and 003 for the county.
What state is Allen County in?
Allen County is in Kentucky.
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.