Oklahoma City is the capital and largest city of the U.S. state of Oklahoma. The county seat of Oklahoma County, the city ranks 31st among United States cities in population. The city's estimated population as of 2008 was 551,789, with an estimated metro-area population of 1,206,142. In 2008, the Oklahoma City-Shawnee Combined Statistical Area had a population of 1,275,758 residents. Besides the core Oklahoma County, Oklahoma City's city limits extend into Canadian, Cleveland, and Pottawatomie counties, though much of those areas are rural or suburban. The city ranks as the seventh-largest city in the United States by land area which includes 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, in the case of Alaska, a borough). The city is the largest city and metro area in population of the traditional 'plains states' as well as the South Central United States outside of Texas. Oklahoma City is an important livestock market, featuring one of the top livestock markets in the world. Oil, natural gas, and petroleum products are a major product of the economy, as the city is situated in the middle of an oil field, with oil derricks even on the capitol grounds. Several prominent Energy companies are headquartered in Oklahoma City. The city has varied light and heavy industries, Tinker Air Force Base and the Federal Government are also vital sources of employment. The city was founded during the Land Run of 1889. The city was the scene of the April 1995 bombing attack of the Alfred P. Murrah Federal Building, in which 168 people lost their lives. It was the worst terror attack in the history of the United States before the terror attacks of September 11, 2001.