No matter where you are in the world, you're probably not far from a Delta hub.

delta airlines hartsfield-jackson atlanta international airport hub
Credit: Ramin Talaie/Corbis via Getty Images

Based at the world’s busiest airport — Hartsfield-Jackson Atlanta International — Delta Air Lines is the oldest carrier based in the United States. (It’s also one of only five legacy carriers, including United Airlines, American Airlines, Alaska Airlines, and Hawaiian Airlines, that survived the 1978 Airline Deregulation Act.)

Delta has carried passengers since 1929. It was originally founded in 1924, though it operated exclusively as a crop-dusting service. In its long history, the airline has used many airports as hubs, from Chicago-O’Hare (until the early 1990s), to Los Angeles-LAX (until the mid-1990s). Germany's Frankfurt airport was a Delta hub until 1997, while Portland, Dallas/Fort Worth, and Orlando all operated as Delta hubs until the early and mid-2000s. Delta was at Memphis until as recently as 2013.

How Delta Hubs Were Acquired

The carrier also inherited some of its current hubs from former airlines. Minneapolis was once the headquarters for the now-defunct Northwest Airlines, for example. (And it's now Delta’s third-largest hub.) Tokyo-Narita is also a former Northwest Airlines hub. Meanwhile, Delta inherited both Los Angeles and Salt Lake City from its 1987 merger with Western Airlines.

Flying Through a Delta Hub

Today, Delta offers upwards of 15,00 flights per day to more than 335 destinations on 6 continents. The airline is regarded for creating the hub-and-spoke system (connecting smaller, national airports to a single, major airport to improve efficiency) now used by many airlines.

While Atlanta is Delta’s largest hub, it uses several other hubs within the United States: Cincinnati, Detroit, Los Angeles, Minneapolis-St. Paul. Salt Lake City, Boston, Seattle-Tacoma, and both LaGuardia as well as John F. Kennedy airports, in New York City. Delta also has international hubs in Paris, London, Amsterdam, and Tokyo.

Atlanta is Delta’s busiest hub by far (with more than 1,000 daily departures to over 220 destinations). That’s more than double the flights of its second most busy hub, Detroit (with 455 daily departures to over 127 destinations). Minneapolis, New York City-LaGuardia, Salt Lake City, and New York City-JFK follow closely behind, with more than 200 daily departures each.

Delta’s international hubs average about 20 flights a day each, with Amsterdam (at 36 daily departures) topping the list.