CITY · SD

What county is Rapid City, SD in?

Rapid City, SD is mostly in Pennington County. County FIPS code 46103, population 115,903 (2023 estimate).

County details

City: Rapid City, South Dakota
Primary county: Pennington County
FIPS code: 46103
County population: 115,903

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

Questions

What county is Rapid City in?

Rapid City, SD is mostly in Pennington County.

What is the county seat of Pennington 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.