Atlanta Airport (ATL)

Also known as ATL, this has been the world’s busiest airport by passenger traffic since 1998 and by number of landings and take-offs more often than not since 2005. Seven miles south of Atlanta’s central business district, the Georgia airport accommodated over 100 million passengers and nearly one million flights in 2012 alone, which breaks down to about 260,000 passengers per day. Most of those flights are domestic. ATL is Delta’s primary hub (it accounts for over 75 percent of the airport’s passengers), and a focus city for Frontier, Southwest, and Spirit.