Dallas is the third-largest city in Texas and the ninth-largest in the United States. Divided between Collin, Dallas, Denton, Kaufman, and Rockwall counties, the city had an estimated 2009 population of approximately 1.3 million, according to the United States Census Bureau. The city is the largest economic center of the 12-county Dallas–Fort Worth–Arlington metropolitan area that according to the March 2010 U.S. Census Bureau release, had a population of roughly 6.5 million as of July 2009. The metropolitan area is the largest metropolitan area in the South and fourth-largest metropolitan area in the United States.