Fort Worth is the fifth-largest city in the state of Texas an the eighteenth-largest city in the United States. Situated in North Texas, Fort Worth covers nearly 300 square miles (780 km²) 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 population now exceeds 700,000 according to a recent 2007 poll. The city is the second-largest cultural and economic center of the Dallas–Fort Worth–Arlington metropolitan area (commonly called the Metroplex). Fort Worth and the surrounding Metroplex area offer numerous business opportunities and a wide array of attractions.