Oklahoma City is the capital and largest city of the state of Oklahoma. The county seat of Oklahoma County, the city ranks 27th among United States cities in population. The population grew following the 2010 Census, with the population estimated to have increased to 631,346 as of July 2015.

As of 2015, the Oklahoma City metropolitan area had a population of 1,358,452  and the Oklahoma City-Shawnee Combined Statistical Area had a population of 1,459,758 (Chamber of Commerce) residents, making it Oklahoma's largest metropolitan area.

Oklahoma City's city-limits extend into Canadian, Cleveland, and Pottawatomie counties, though much of those areas outside of the core Oklahoma County area are suburban or rural (watershed).

The city ranks as the eighth-largest city in the United States by land area (including consolidated city-counties; it is the largest city in the United States by land area whose government is not consolidated with that of a county or borough).