Rapid Creek is a tributary of the Cheyenne River, approximately 86 mi (138 km) long, in South Dakota, United States. The creek's name comes from the Sioux Indians of the area, for the many rapids in the stream.
It rises in southwestern South Dakota, in the Black Hills National Forest in Pennington County. It flows east, is joined by Castle Creek, past Silver City and through the Pactola Reservoir. Emerging from the Black Hills, it flows through Rapid City, past Farmingdale, and joins the Cheyenne River approximately 13 mi (21 km) southwest of Wasta.
The Rapid Creek is most noted for the Black Hills flood of 1972, in which 238 people perished in Rapid City and the Black Hills area. Since the flood, a flood plain has been established throughout the city making development along the banks inconsiderable.