COUNTY · IA
O'Brien County, Iowa
O'Brien County is a county in Iowa with FIPS code 19141 and an estimated population of 14,012 (Census 2023), 57th largest of 99 in the state.
County facts
- Name
- O'Brien County
- State
- Iowa
- Type
- county
- FIPS code
- 19141
- State FIPS
- 19
- Population (2023)
- 14,012
- Change since 2020
- -1.0%
- State rank
- 57 of 99
Population is the Census Bureau’s Vintage 2023 estimate.
Questions
What is the FIPS code for O'Brien County?
O'Brien County, Iowa has the five-digit FIPS code 19141: 19 for the state and 141 for the county.
What state is O'Brien County in?
O'Brien 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.