The Atlanta metropolitan area, commonly referre to as metro Atlanta in Georgia, is the ninth-largest metropolitan area in the United States and consists of 28 counties in Georgia. According to the 2000 Census, the metropolitan area had a population of 4,247,981, though the 2007 Census estimate shows 5,278,904 people living in the area. According to the 2007 population estimates, the 28-county Atlanta metropolitan area is currently the fastest-growing metropolitan area in the United States based on numerical gains. The city of Atlanta is only the 35th-largest city in the country, largely due to the area's patterns of urban sprawl and the city's inability to annex as have such cities as Charlotte, San Diego, Dallas, Houston and Phoenix. Atlanta's combined statistical area, or CSA, had a population in 2000 of 4,584,234. As of July 1, 2007 the population of the CSA is estimated to be 5,626,400.