CITY · MO

What county is St. Louis, MO in?

St. Louis, MO is mostly in St. Louis city. County FIPS code 29510, population 281,754 (2023 estimate).

County details

City: St. Louis, Missouri
Primary county: St. Louis city
FIPS code: 29510
County population: 281,754

Some cities extend into more than one county. St. Louis is placed in the county that contains its center. For a specific address, use the address lookup.

Questions

What county is St. Louis in?

St. Louis, MO is mostly in St. Louis city.

What is the county seat of St. Louis city?

County seats are not part of the data on this site. Check the county’s official website.

Can a city be in two counties?

Yes. Large cities such as Houston and Atlanta cross county lines. The address lookup shows the exact county for any street address.

Sources: U.S. Census Bureau geographic reference files; FCC Area API; Census Bureau Population Estimates, Vintage 2023. Last reviewed 2026-10-27.