CITY · IN

What county is Indianapolis, IN in?

Indianapolis, IN is mostly in Marion County. County FIPS code 18097, population 968,460 (2023 estimate).

County details

City: Indianapolis, Indiana
Primary county: Marion County
FIPS code: 18097
County population: 968,460

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

Questions

What county is Indianapolis in?

Indianapolis, IN is mostly in Marion County.

What is the county seat of Marion County?

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.