Hartsfield-Jackson Atlanta International Airport traces its origins to April 1925, when Atlanta's mayor signed a lease on an abandoned auto racetrack on the city's south side. The site was renamed Candler Field after its former owner, Coca-Cola magnate Asa Candler. The first commercial flight arrived on September 15, 1926, a Florida Airways mail plane from Jacksonville, Florida, drawing more than 15,000 spectators. It was busy from the start.

Delta Air Service began flying from Atlanta in June 1930, establishing what would become the airport's dominant airline relationship. During World War II the facility doubled in size under military control, setting a single-day record of 1,700 operations. After the war, passenger traffic surged. By 1957, Atlanta had become the busiest airport in the United States. The current midfield terminal complex, one of the largest construction projects in the South at the time, costing $500 million, opened September 21, 1980, and was designed to handle up to 55 million passengers per year. In 2012, the Maynard H. Jackson Jr. International Terminal opened on the east side of the airport, adding dedicated international facilities connected to seven concourses via an underground automated people mover called the Plane Train.

Today, ATL is the primary hub and global headquarters of Delta Air Lines, which operates more than 1,000 daily flights from the airport to 225 destinations. The airport has held the title of world's busiest by passenger traffic every year since 1998, with the single exception of 2020. In 2024 it served 108 million passengers. Located about 10 miles south of downtown Atlanta, the airport sits mostly in unincorporated Clayton County and is directly connected to the city's MARTA rail network, making it one of the few major U.S. airports with dedicated rapid transit access.