Oklahoma City ( (listen)), officially the City of Oklahoma City, and often shortened to OKC, is the capital and largest city of the U.S. state of Oklahoma. The county seat of Oklahoma County, it ranks 22nd among United States cities in population, and is the 11th largest city in the Southern United States. The population grew following the 2010 census and reached 681,054 in the 2020 census. 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, 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 is the eighth-largest in the United States by area including consolidated city-counties; it is the second-largest, after Houston, not including consolidated cities. The city is also the second largest by area among state capital cities in the United States, after Juneau, Alaska. Oklahoma City has one of the world's largest livestock markets. Oil, natural gas, petroleum products and related industries are its economy's largest sector. The city is in the middle of an active oil field and oil derricks dot the capitol grounds. The federal government employs a large number of workers at Tinker Air Force Base and the United States Department of Transportation's Mike Monroney Aeronautical Center (which house offices of the Federal Aviation Administration and the Transportation Department's Enterprise Service Center, respectively). Oklahoma City is on the I-35 Corridor, 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. It was the scene of the April 19, 1995, bombing of the Alfred P. Murrah Federal Building, in which 168 people died, the deadliest terror attack in U.S. history until the attacks of September 11, 2001, and the deadliest act of domestic terrorism in U.S. history. Since weather records have been kept, Oklahoma City has been struck by 13 violent tornadoes, 11 of which were rated F4 or EF4 on the Fujita and Enhanced Fujita scales, and two F5 or EF5.

Northwestern Oklahoma is the geographical region of the state of Oklahoma which includes the Oklahoma Panhandle and a majority of the Cherokee Outlet, stretching to an eastern extent along Interstate 35, and its southern extent along the Canadian River to Noble County. Northwest Oklahoma is also known by its Oklahoma Department of Tourism designation, Red Carpet Country, which is named after the region's red soil and alludes to the metaphor that the panhandle is a "red carpet" into Oklahoma. The region consists of Cimarron, Texas, Beaver, Harper, Woods, Alfalfa, Grant, Kay, Ellis, Woodward, Major, Garfield, Noble, Dewey, Blaine, and Kingfisher counties. The area is anchored economically by Enid, which also contains the region's largest commercial airport. Other important cities include Guymon, Ponca City, Woodward, and Alva.

Little Dixie is a name given to southeast Oklahoma, which in the past was strongly influenced by southern "Dixie" culture as its white settlers were chiefly Southerners seeking a start in new lands following the American Civil War. In addition, it incorporated lands of some of the Five Civilized Tribes who had been removed from the Southeast. A number were slaveholders, and they generally allied with the Confederacy during the Civil War. The Oklahoma tourism department also refers to this area as "Choctaw Country," formerly "Kiamichi Country," but the Little Dixie region is not clearly defined: its exact boundaries vary by source. It falls mostly within the Choctaw Nation of Oklahoma's tribal area, as well as some Chickasaw and Muscogee Creek lands. During the tenure of US Representative Carl Albert, it was still the 3rd Congressional district of Oklahoma. Redistricting has since changed the geographical boundariesSeveral towns and cities in southeast Oklahoma use the Little Dixie name, and that helps to define the boundaries. A radio station in McAlester is owned by "Little Dixie Radio, Inc." The band at the public high school in Tishomingo, former capital of the Chickasaw Nation, is called The Pride of Little Dixie. When President Harry Truman visited Marietta in Love County in 1948, he gave a speech saying it was a pleasure to be in the Little Dixie region of Oklahoma.Leaves of Grass, a 2010 film starring Edward Norton, is set mostly in Little Dixie.

Southwest Oklahoma is a geographical name for the southwest portion of the state of Oklahoma, typically considered to be south of the Canadian River, extending eastward from the Texas border to a line roughly from Weatherford, to Anadarko, to Duncan. Geologically, the region is defined by a failed continental rift known as the Southern Oklahoma Aulacogen. The austere nature of the prairie landscape with intermittent island ranges has made it a favorable place for artists and photographers alike. For tourism purposes, the Oklahoma Tourism and Recreation Department has designated Southwestern Oklahoma as Great Plains Country, and defined it to consist of 14 counties including Roger Mills, Custer, Beckham, Washita, Caddo, Kiowa, Greer, Harmon, Jackson, Comanche, Tillman, Cotton, Stephens, and Jefferson counties. Anchored by Lawton, its largest city, Southwest Oklahoma's other important urban centers include Elk City, Clinton, Weatherford, Walters, Altus, and Duncan.