Arlington is a city in the U.S. state of Texas, within the Dallas–Fort Worth–Arlington metropolitan area and Tarrant County. According to the U.S. Census Bureau's estimate, the city had a population of almost 379,577 at the end of 2013, making it the third largest municipality in the metropolitan area. Arlington is the fiftieth most populous city in the United States, the seventh most populous city in the state of Texas, and the largest city in the state that is not a county seat.