Arlington is the 50th-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.Īrlington is home to the University of Texas at Arlington, a major urban research university, the Arlington Assembly plant used by General Motors, the Nuclear Regulatory Commission Region IV, Texas Health Resources, Mensa International, and D. The city had a population of 394,266 in 2020, making it the second-largest city in the county, after Fort Worth, and the third-largest city in the metropolitan area, after Dallas and Fort Worth. It forms part of the Mid-Cities region of the Dallas–Fort Worth–Arlington metropolitan statistical area, and is a principal city of the metropolis and region. state of Texas, located in Tarrant County.