is the second-largest city in the U.S. state of South Dakota, and the county seat of Pennington County. Named after the Rapid Creek on which the city is established, it is set against the eastern slope of the Black Hills mountain range. Rapid City had a population of 59,607 at the 2000 census. Rapid City is known as the "Gateway to the Black Hills" and the "Star of the West". The city is divided by a mountain range that splits the western and eastern parts of the city into two.
Rapid City is located at . The downtown elevation of Rapid City is 3,202 feet (976 m) and Rapid City sits in the shadow of Harney Peak; which at , is the highest point east of the Rocky Mountains.
According to the United States Census Bureau, the city has a total area of 44.7 sq mi (115.7 km
). 44.6 sq mi (115.5 km
Rapid City has been assigned the ZIP code range 57701-57709 and the FIPS place code 52980.
Rapid City is located on the eastern edge of the Black Hills, and is split in half by the Dakota Hogback. Rapid City's "Westside" is located in the Red Valley between the foothills of the Black Hills proper and the Dakota Hogback, so named for the red Spearfish formation soils and the way the valley completely circles the Black Hills. Rapid City has grown up into the foothills, with both ridges and valleys developed, especially in the last 20 years, and wildfire is a distinct threat to these residential areas, as shown by the Westberry Trails fire in 1988.
Skyline Drive follows the summits of the Dakota Hogback south from near Rapid Gap (where Rapid Creek cuts through the Hogback) to a large high plateau which forms the current south edge of Rapid City. The Central and Eastern portions of Rapid Creek lie in the wide valley of Rapid Creek outside the Hogback, which includes a number of mesas rising a hundred feet or more above the floodplain.