It has been the US and the world's busiest airport by passenger traffic since 1998; and by number of landings and take-offs from 2005 to 2013, losing that title to Chicago-O'Hare in 2014, but regaining it a year later. Hartsfield–Jackson held its ranking as the world's busiest airport in 2012, both in passengers and number of flights, by accommodating 100 million passengers (more than 260,000 passengers daily) and 950,119 flights. Many of the nearly one million flights are domestic flights from within the United States, where the airport serves as a major hub for travel throughout the southeastern region of the country. The airport has 207 domestic and international gates.
Hartsfield–Jackson is the primary hub of Delta Air Lines, and is a focus city for low-cost carriers Frontier Airlines, Southwest Airlines, and Spirit Airlines. With just over 1,000 flights a day, the Delta Air Lines hub is the world's largest hub. Delta Air Lines flew 75.4% of the airport's passengers in February 2016, Southwest flew 9.2%, and American Airlines flew 2.5%. In addition to hosting Delta Air Lines corporate headquarters, Hartsfield–Jackson is also the home of Delta's Technical Operations Center, which is the airline's primary maintenance, repair and overhaul arm. The airport has international service within North America and to countries in South America, Central America, Europe, Asia, and Africa. As an international gateway to the United States, Hartsfield–Jackson ranks sixth.
The airport is mostly in unincorporated areas in Fulton and Clayton counties. However, the airport spills into the city limits of Atlanta, College Park, and Hapeville. The airport's domestic terminal is served by MARTA's Red and Gold rail lines.