Atlanta is the capital and most populous city in the U.S. state of Georgia, as well as the urban core of one of the fastest-growing metropolitan areas in the United States. With a 2008 estimated population of 537,958, Atlanta is the thirty-third largest city in the United States, and the 28-county Atlanta Metropolitan Area is the eighth largest such region in the United States, and the second largest in the Southeastern U.S. , behind Miami-Fort Lauderdale, with more than 5,376,285 residents. The Atlanta Combined Statistical Area, home to 5,729,304 people, is the eighth largest in the country. Considered a top business city and transportation hub, Atlanta is the world headquarters of The Coca-Cola Company, AT&T Mobility, and Delta Air Lines. The surrounding area contains additional corporate headquarters, including Home Depot and UPS. Atlanta has the country's third largest concentration of Fortune 500 companies along with Chicago and Minneapolis, although Home Depot, Newell Rubbermaid, and UPS are not located within city limits but are counted as being in the city, and more than 75 percent of the Fortune 1000 companies have a presence in the Atlanta metropolitan area. The Atlanta metropolitan area has the tenth largest concentration of Fortune 500 headquarters tied with Boston, Cleveland, and Denver. Hartsfield–Jackson Atlanta International Airport, which is located seven miles south of downtown Atlanta, is the world's busiest airport and the only major airport to serve the city. Atlanta is the county seat of Fulton County and the fifth location for the seat of government of the state of Georgia. A small portion of the city of Atlanta corporate limits extends into DeKalb County. Residents of the city are known as Atlantans.