Spearfish is a city in Lawrence County, South Dakota, United States. The population was 12,193 at the time of the 2020 census, making it the 10th most populous city in South Dakota. Spearfish is the largest city in Lawrence County and the home of Black Hills State University.

Lawrence County is a county in the U.S. state of South Dakota. As of the 2020 census, the population was 25,768, making it the 8th most populous county in South Dakota. Its county seat is Deadwood.