COUNTY · IL
Washington County, Illinois
Washington County is a county in Illinois with FIPS code 17189 and an estimated population of 13,536 (Census 2023), 76th largest of 102 in the state.
County facts
- Name
- Washington County
- State
- Illinois
- Type
- county
- FIPS code
- 17189
- State FIPS
- 17
- Population (2023)
- 13,536
- Change since 2020
- -1.4%
- State rank
- 76 of 102
Population is the Census Bureau’s Vintage 2023 estimate.
Questions
What is the FIPS code for Washington County?
Washington County, Illinois has the five-digit FIPS code 17189: 17 for the state and 189 for the county.
What state is Washington County in?
Washington County is in Illinois.
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.