Rapid City
- County:
- Pennington County
- County Seat:
- No
- Area (mi²):
- 55.987
- State:
- South Dakota
Rapid City is a city located in Pennington County, South Dakota. Rapid City has a 2026 population of 79,894. Rapid City is currently growing at a rate of 0.65% annually and its population has increased by 6.61% since the most recent census, which recorded a population of 74,943 in 2020.