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 610,613 as of July 2013. As of 2013, the Oklahoma City metropolitan area had a population of 1,319,677, and the Oklahoma City-Shawnee Combined Statistical Area had a population of 1,390,835 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 second-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). Oklahoma City is on the I-35 Corridor as one of the primary travel corridors into neighboring Texas and Mexico. Located in the Frontier Country region of the state, 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 nine strong tornadoes, eight F/EF4s and one F5.