Oklahoma City ( OH-klə-HOH-mə -⁠), often shortened to OKC, is the capital and most populous city in the U.S. state of Oklahoma. It is the 21st-most populous U.S. city and 8th largest in the Southern United States, with a population of 681,054 at the 2020 census. It is the county seat of Oklahoma County, with the city limits extending into Canadian, Cleveland, and Pottawatomie counties; however, areas beyond Oklahoma County primarily consist of suburban developments or areas designated rural and watershed zones.