Why America’s Busiest Airport Is Still Running On Air Traffic Software Built Before The iPhone Existed

There are various ways to grade how “busy” an airport is, and this impacts the rankings. The busiest airport is typically regarded to be Hartsfield-Jackson Atlanta International Airport as it has the most passengers annually (106.3 million in 2025). However, Chicago O’Hare also lays claim to being the busiest airport in the United States by number of takeoffs and landings. In 2025, O’Hare had 857,392 aircraft movements, placing it ahead of Atlanta’s 805,268 movements.