Arlington is a city in Tarrant County, Texas (USA) within the DallasâFort Worth metropolitan area. According to the U.S. Census Bureau's estimate, the city had a population of almost 374,000 at the end of 2011, making it the third largest municipality in the Metroplex. Arlington is the fiftieth most populous city in the United States of America and the seventh most populous city in the state of Texas; it is also the largest city in the state that is not a county seat.
Located approximately 12 miles (19 km) east of downtown Fort Worth and 20 miles (32 km) west of downtown Dallas, Arlington is home to the University of Texas at Arlington, a doctoral-granting institution, and a General Motors assembly plant. Additionally Arlington hosts the Texas Rangers' Rangers Ballpark in Arlington, Cowboys Stadium, the International Bowling Campus (which houses the United States Bowling Congress, International Bowling Museum and the International Bowling Hall of Fame), the headquarters for American Mensa, and the theme parks Six Flags Over Texas (the original Six Flags) and Hurricane Harbor. The city borders Kennedale, Grand Prairie, Mansfield and Fort Worth, and surrounds the smaller communities of Dalworthington Gardens and Pantego. Arlington is the headquarters of the Nuclear Regulatory Commission Region IV.