John F. Kennedy International Airport (JFK) in New York City serves as a hub for Delta Air Lines, Jet Blue and American Airlines. Baltimore-Washington International Airport is a hub for Air Tran, while Charlotte and Philadelphia are hubs for US Airways. Atlanta's Hartsfield-Jackson Atlanta International Airport is a major hub for Delta and Air Tran.
O'Hare Airport in Chicago is one of the busiest hubs in the country, serving United Airlines and American Airlines. Milwaukee's General Mitchell International Airport serves as a hub for Air Tran, Frontier Airlines and Midwest Airlines. Dallas-Fort Worth, the eighth busiest airport in the world, serves as a hub for American Airlines. Detroit Metropolitan Wayne County Airport is a hub for Delta and Spirit Airlines.
The west coast is home to a few very large hubs. Los Angeles International Airport (LAX), a hub for Alaska Airlines, American Airlines and United airlines, is the sixth busiest airport in the world. Phoenix's Sky Harbor Airport is a hub for US Airways and low fare carrier Southwest Airlines. Further up the California coast, San Fransisco International Airport is a hub for United Airlines and Virgin America.