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 374,000 at the end of 2011,  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. Arlington is the largest city in the United States without a comprehensive public transit system. 
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 , AT&T 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 . Arlington is the headquarters of the Nuclear Regulatory Commission Region IV .
Arlington borders Kennedale , Grand Prairie , Mansfield and Fort Worth , and surrounds the smaller communities of Dalworthington Gardens and Pantego .