San Antonio is the second-largest city in the state of Texas and the seventh-largest city in the United States with a population of 1.3 million. The city is the seat of Bexar County. Located in the American Southwest and the northern part of South Texas, San Antonio is the center of Tejano culture and Texas tourism. The city is characteristic of other Southwest urban centers in which there are sparsely populated areas and a low density rate outside of the city. It was the fourth-fastest growing large city in the nation from 2000 to 2006 and the fifth-fastest-growing from 2007 to 2008. The San Antonio–New Braunfels metropolitan area has a population of 2 million based on the 2008 U.S. Census estimate, making it the 28th-largest metropolitan area in the U. S and third in Texas. The city was named for the Portuguese St. Anthony, whose feast day is on June 13, when a Spanish expedition stopped in the area in 1691. Famous for Spanish missions, the Alamo, the River Walk, the Tower of the Americas, the Alamo Bowl, and host to Seaworld and Six Flags Fiesta Texas theme parks, the city is visited by approximately 26 million tourists per year according to the San Antonio Convention and Visitors Bureau. The city is home to the four-time NBA champion San Antonio Spurs and the annual San Antonio Stock Show & Rodeo, one of the largest in the country. San Antonio has a strong military presence—it is home to Fort Sam Houston, Lackland Air Force Base, Randolph Air Force Base, and Brooks City-Base, with Camp Bullis and Camp Stanley outside the city. Kelly Air Force Base operated out of San Antonio until 2001, when the airfield was transferred over to Lackland AFB and the remaining portions of the base became Port San Antonio, an industrial/business park. San Antonio is home to five Fortune 500 companies and to the South Texas Medical Center, the only medical research and care provider in the South Texas region.