The Rapid City, SD metropolitan area, as defined by the United States Census Bureau. Anchored by the city of Rapid City, the area corresponds to the entirety of Pennington and Meade counties in the state of South Dakota, though the Rapid City market area extends well beyond those counties and into Nebraska, Montana, Wyoming, and North Dakota. The population was 139,074 at the 2020 census. According to 2022 census estimates, the MSA is estimated to have a population of 145,159.

Pennington County is a county in the U.S. state of South Dakota. As of the 2020 census, the population was 109,222, making it the second most populous county in South Dakota. Its county seat is Rapid City. The county was created in 1875, and was organized in 1877. It is named for John L. Pennington, fifth Governor of Dakota Territory, who held office in 1875 when the county was formed.