The world's busiest airports by passenger traffic are measured by total passengers provided by the Airports Council International, defined as passengers enplaned plus passengers deplaned plus direct-transit passengers. The world's busiest airport is Hartsfield–Jackson Atlanta International Airport in metropolitan Atlanta, Georgia, which has been the world's busiest airport every year since 1998 with the exception of 2020, when its passenger traffic dipped for a year due to travel restrictions resulting from the COVID-19 pandemic. Atlanta regained the top position in 2021, and has held it since. Alternatively, London has the world's busiest city airport system by passenger count.