Richland County is located in the U.S. state of South Carolina. As of the 2020 census, its population was 416,147, making it the second-most populous county in South Carolina, behind only Greenville County. The county seat and largest community is Columbia, the state capital. The county was established on March 12, 1785. Richland County is part of the Columbia, SC Metropolitan Statistical Area. In 2020, the center of population of South Carolina was located in Richland County, in the city of Columbia. The county is also the location of the geographic center of South Carolina, southeast of Columbia.

Columbia is the capital city of the U.S. state of South Carolina. With a population of 136,632 at the 2020 census, it is the second-most populous city in South Carolina. The city serves as the county seat of Richland County, and a portion of the city extends into neighboring Lexington County. It is the center of the Columbia, SC Metropolitan Statistical Area, which had an estimated population of 858,302 in 2023, and is the 70th-most populous metropolitan statistical area in the United States. The name Columbia is a poetic term used for the United States, derived from the name of Christopher Columbus, who explored for the Spanish Crown. Columbia is often abbreviated as Cola, leading to its nickname as "Soda City".