Oklahoma City is the capital and the largest city in the US state of Oklahoma. The county seat of Oklahoma County, the city ranks 31st among United States cities in population. The city's population, from the 2010 census, was 579,999, with a metro-area population of 1,252,987. In 2010, the Oklahoma City-Shawnee Combined Statistical Area had a population of 1,322,249 residents. 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).

Oklahoma City features one of the largest livestock markets in the world. Oil, natural gas, petroleum products and related industries are the largest sector of the local economy. The city is situated 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.)

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 attack of the Alfred P. Murrah Federal Building, in which 168 people died. It was the worst terror attack in the history of the United States before the attacks of September 11, 2001, and remains the worst act of domestic terrorism in U.S. history.

Oklahoma City lies along one of the primary travel corridors into Texas and Mexico, and is about three hours by highway to the Dallas-Fort Worth metropolitan area. Located in the Frontier Country region of the state, the city's northeast section lies in an ecological region known as the Cross Timbers. Since the time weather records have been kept, Oklahoma City has been struck by nine strong tornadoes, eight (E)-F4's and one F5. On May 3, 1999 parts of southern Oklahoma City and nearby communities suffered one of the most powerful tornadoes on record.

Oklahoma City was settled on April 23, 1889, when the area known as the "unassigned lands" was opened for European-American settlement in an event known as "The Land Run". Some 10,000 homesteaders settled the area that would become the capital of Oklahoma. The town grew quickly; the population doubled between 1890 and 1900. Early leaders of the development of the city included Anton Classen, John Shartel, Henry Overholser and James W. Maney.

By the time Oklahoma was admitted to the Union in 1907, Oklahoma City had surpassed Guthrie, the territorial capital, as the population center and commercial hub of the new state. Soon after, the capital was moved from Guthrie to Oklahoma City. Oklahoma City was a major stop on Route 66 during the early part of the 20th century; it was prominently mentioned in Bobby Troup's 1946 jazz classic, "(Get Your Kicks on) Route 66", later made famous by Nat King Cole.

Before World War II, Oklahoma City developed major stockyards, attracting jobs and revenue formerly in Chicago and Omaha. With the 1928 discovery of oil within the city limits (including under the State Capitol), it became a center of oil production. Post-war growth accompanied the construction of the Interstate Highway System, which made Oklahoma City a major interchange as the convergence of I-35, I-40 and I-44. It was also aided by federal development of Tinker Air Force Base.

As with many other American cities, center city population declined in the 1970s and 80s as families followed newly constructed highways to move to newer housing in nearby suburbs. Urban renewal projects in the 1970s, including the Pei Plan (Oklahoma City), removed many older historic structures but failed to spark much new development, leaving the city dotted with vacant lots used for parking. A notable exception was the city's construction of the Myriad Gardens and Crystal Bridge, a botanical garden and modernistic conservatory in the heart of downtown. Architecturally significant historic buildings lost to clearances were the Criterion Theater, the Baum Building, the Hales Building, and the Biltmore Hotel.

In 1993, the city passed a massive redevelopment package known as the Metropolitan Area Projects (MAPS), intended to rebuild the city's core with civic projects to establish more activities and life to downtown. The city added a new baseball park; central library; renovations to the civic center, convention center and fairgrounds; and a water canal in the Bricktown entertainment district. Water taxis transport passengers within the district, adding color and activity along the canal. MAPS has become one of the most successful public-private partnerships undertaken in the U.S., exceeding $3 billion in investments. As a result of MAPS, the population living in downtown housing has greatly increased, together with demand for residential amenities, such as grocery, services and other retail stores.

Since the MAPS projects' completion, the downtown area has seen continued development. Several downtown buildings are undergoing renovation/restoration. Notable among these was the restoration of the Skirvin Hotel in 2007. The famed First National Center is being renovated.

Residents of Oklahoma City suffered substantial losses on April 19, 1995 when Timothy McVeigh set off a bomb in front of the Murrah building. The building was destroyed, more than 100 nearby buildings suffered severe damage, and 168 people were killed. The site has been commemorated as the Oklahoma City National Memorial and Museum. Since its opening in 2000, over 3 million people have visited. Every year on April 19, survivors, families and friends return to the memorial to read the names of each person lost.

The "Core-to-Shore" project was created to relocate I-40 one mile (1.6 km) south and replace it with a boulevard to create a landscaped entrance to the city. This also allows the central portion of the city to expand south and connect with the shore of the Oklahoma River. Several elements of "Core to Shore" were included in the MAPS 3 proposal approved by voters in late 2009.

Lake Hefner is a reservoir in northwestern Oklahoma City, Oklahoma. It was built in 1947 to expand the water supply for the city of Oklahoma City. It also serves as a major recreational destination, as it is surrounded by 9.5 miles (15.3 km) of bicycle trails. Lake Hefner covers 2,500 acres (10 km²) and averages 29 feet (9 m) deep. It is named after Robert A. Hefner, who served as mayor of Oklahoma City from April 11, 1939 to April 8, 1947. 

The lake is situated within the Oklahoma City urban area and is subsequently closely bordered by residential areas to the north, west, and east. The Lake Hefner Dam is located along the entire northern side of the lake. The Lake Hefner Parkway borders the east side of the lake. The south side is the least developed, retaining the original forest along much of the shore. The Lake Hefner Golf Course is located on the southwest corner of the lake. Immediately south of this are the Oklahoma City docks, commonly known as the city-side docks, the largest marina on the lake. The other marina on Lake Hefner is the Oklahoma City Boat Club, a private organization that holds weekly sailboat races during the summer and is located on the east side. Just north of the OCBC is the East Wharf area, which contains several fairly upscale restaurants. On the south side of the lake is the YMCA Sailing Center, and Stars and Stripes Park.