COUNTY · OK
McClain County, Oklahoma
McClain County is a county in Oklahoma with FIPS code 40087 and an estimated population of 47,072 (Census 2023), 20th largest of 77 in the state.
County facts
- Name
- McClain County
- State
- Oklahoma
- Type
- county
- FIPS code
- 40087
- State FIPS
- 40
- Population (2023)
- 47,072
- Change since 2020
- +12.3%
- State rank
- 20 of 77
Population is the Census Bureau’s Vintage 2023 estimate.
Questions
What is the FIPS code for McClain County?
McClain County, Oklahoma has the five-digit FIPS code 40087: 40 for the state and 087 for the county.
What state is McClain County in?
McClain County is in Oklahoma.
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.