One might expect the world’s busiest airport to be located in New York or London or Beijing, but the distinction actually belongs to Hartsfield-Jackson Atlanta International Airport, located in the southern US city of Atlanta, Georgia. No matter which way you calculate it, Hartsfield-Jackson has been the world’s busiest since 1998. Not only does it attract more travellers than any other airport in the world (with about 92.4 million passengers passing through in 2011, the last full year on record), it also manages more aircraft movements (that is, more takeoffs and landings) than any airport in the world – with about 950,000 in 2010, also the last year on record.

All of this begs the question, why is Atlanta the busiest hub for air travel in the world?

The Delta factor

Atlanta is home to one of the world’s largest airlines. Delta Air Lines was founded in the city of Macon, Georgia (originally as a crop-dusting company called Huff Daland Dusters) and later moved its headquarters about 85 miles north to Atlanta in 1941 (after running its first passenger flights under the name Delta Air Service in 1929).

Until 2012, Delta held the record for most annual traffic – measured by “revenue passenger miles” (RPM) – of any airline in the world. The metric of RPMs takes into account both the number of passengers carried and the distances an airline flew during a given year. In 2012 though, Delta’s RPM was beaten by United Airlines, which had grown in size following the 2010 merger between United and Continental Airlines.

So it makes sense, then, that Chicago, home to United’s headquarters, hosts the world’s second busiest airport as measured by aircraft movements – with 882,627 in 2010 – and the world’s fourth busiest as measured by sheer passenger numbers – with 66.6 million passengers in 2011. (The second and third busiest by number of passengers in 2011 are Beijing Capital International Airport, with 77.4 million and London Heathrow Airport with 69.4 million)

Hartsfield-Jackson serves 225 destinations in 51 countries, receives more than 250,000 passengers a day, and sees nearly 2,500 arrivals and departures per day. Out of this, Delta runs about 1,000 flights daily, serving more than 200 destinations.

The location

According to data collected by Hartsfield-Jackson Airport, Atlanta is located within a two-hour flight of 80% of the US population, making the city a major port of entry into the US and a logical stopover for travel within the expansive country.

Hartsfield-Jackson is also the only airport located in Atlanta and by far the biggest airport in Georgia. Most other major hub cities, such as New York, split traffic between two or more major airports. The nearest major airport to Hartsfield-Jackson, is 250 miles northwest, in Nashville, Tennessee.

The city

Hartsfield-Jackson also happens to be located in a city that attracts its fair share of travellers. Atlanta has been ranked the seventh most visited city for business travel in the US – unsurprising, since it is home to the headquarters of 10 Fortune 500 companies, including Coca-Cola, Home Depot (a massive home improvement retailer), UPS (the United Parcel Service) and, of course, Delta Air Lines.

For non-business visitors, Atlanta is also home to perhaps the world’s largest aquarium, where visitors can find the biggest fish on Earth. Rivalled only by the new SEA Aquarium in Singapore (which also calls itself the world’s largest), the Georgia Aquarium holds more than 8 million gallons of water and provides habitat to around 120,000 animals, according to aquarium statistics.

Atlanta’s big companies also offer behind-the-scenes tours popular with all kinds of travellers. Coca Cola offers an attraction called The World of Coca-Cola, a sort of museum taking tourists into the history of one of the planet’s most consumed beverages. CNN, the 24-hour cable news channel available around the world, has a popular Inside CNN Studio Tour.

If you find yourself enduring the all-too-common layover in Hartsfield-Jackson Atlanta International Airport, Jaunted offers five ideas for passing the time – including renting out a room at the airport’s unique Minute Suites, which let you rent out a private room by the hour or for the night in Terminal B, and dining at the upscale “southernnational” joint One Flew South, a restaurant in Terminal E incorporating southern ingredients and techniques to international cuisine fit for the typical Hartsfield traveller.

For more on travel to Atlanta, Lonely Planet offers these tips for top attractions to hit.

Travelwise is a BBC Travel column that goes behind the travel stories to answer common questions, satisfy uncommon curiosities and uncover some of the mystery surrounding travel. If you have a burning travel question, contact Travelwise.