San Antonio, officially the City of San Antonio, is the seventh-most populated city in the United States and the second-most populous city in the state of Texas, with a population of 1,409,019. It was the fastest growing of the top 10 largest cities in the United States from 2000 to 2010, and the second from 1990 to 2000. The city straddles South Texas and Central Texas and is on the southwestern corner of an urban megaregion known as the Texas Triangle.San Antonio serves as the seat of Bexar County. Recent annexations have extended the city’s boundaries into Medina County and, though for only a very tiny area near the city of Garden Ridge, into Comal County. Due to its placement, the city has characteristics of other western urban centers in which there are sparsely populated areas and a low density rate outside of the city limits. San Antonio is the center of the San Antonio–New Braunfels Metropolitan Statistical Area. Commonly referred to as Greater San Antonio, the metropolitan area has a population of nearly 2.4 million based on the 2015 US Census estimate, making it the 25th-largest metropolitan area in the United States and third-largest in the state of Texas. Growth along the Interstate 35 and Interstate 10 corridors to the north, west and east make it likely that the metropolitan area will continue to expand.