Houston (pronounce /ˈhjuːstən/) is the fourth-largest city in the United States of America and the largest city within the state of Texas. As of the 2006 U.S. Census estimate, the city has a population of 2.14 million within an area of 600 square miles (1,600 km²). Houston is the seat of Harris County and the economic center of the Houston–Sugar Land–Baytown metropolitan area—the sixth-largest metropolitan area in the U.S. with a population of around 5.6 million.