Oklahoma City (), often shortened to OKC, is the capital and largest city of the U.S. 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 649,021 as of July 2018. The Oklahoma City metropolitan area had a population of 1,396,445, and the Oklahoma City-Shawnee Combined Statistical Area had a population of 1,469,124 residents, making it Oklahoma's largest municipality and metropolitan area by population.
Oklahoma City's city limits extend somewhat into Canadian, Cleveland, and Pottawatomie counties, though much of those areas outside the core Oklahoma County area are suburban tracts or protected rural zones (watershed). The city ranks as the ninth-largest city in the United States by total area when including consolidated city-counties; it is the second largest city in the United States by total area, following Houston, when not including consolidated cities.
Lying in the Great Plains region, Oklahoma City has one of the world's largest livestock markets. Oil, natural gas, petroleum products and related industries are the largest sector of the local economy. The city is in the middle of an active oil field and oil derricks dot the capitol grounds. The federal government employs large numbers of workers at Tinker Air Force Base and the United States Department of Transportation's Mike Monroney Aeronautical Center (these two sites house several offices of the Federal Aviation Administration and the Transportation Department's Enterprise Service Center, respectively).
Oklahoma City is on the I-35 Corridor, which is one of the primary travel corridors south into neighboring Texas and Mexico and north towards Wichita and Kansas City. Located in the state's Frontier Country region, the city's northeast section lies in an ecological region known as the Cross Timbers. The city was founded during the Land Run of 1889 and grew to a population of over 10,000 within hours of its founding. The city was the scene of the April 19, 1995 bombing of the Alfred P. Murrah Federal Building, in which 168 people died. It was the deadliest terror attack in the history of the United States until the attacks of September 11, 2001, and remains the deadliest act of domestic terrorism in U.S. history.
Since the time weather records have been kept, Oklahoma City has been struck by thirteen strong tornadoes; eleven of these tornadoes were rated F4 or EF4 on the Fujita and Enhanced Fujita scales, and two were rated F5 or EF5.Since 2008, Oklahoma City has been home to the National Basketball Association (NBA)'s Oklahoma City Thunder, who play their home games at the Chesapeake Energy Arena.