Fort Worth is the fifth-largest city in the state of Texas, 18th-largest city in the United States, and voted one of America’s Most Livable Communities. Situated in North Texas, Fort Worth covers nearly 300 square miles in Tarrant and Denton counties, serving as the county seat for Tarrant County. As of the 2006 U.S. Census estimate, Fort Worth had a population of 653,320. The city is the second-largest cultural and economic center of the Dallas--Fort Worth--Arlington metropolitan area (commonly called the Metroplex), the fourth-largest metropolitan area in the U.S. with a population of 6 million in twelve counties.