List of busiest city airport systems by passenger traffic

The world's busiest city airport systems by passenger traffic are measured by total number of passengers from all airports within a city or metropolitan area combined. London, with six commercial airports serving its metropolitan area, is the busiest city airport system in the world, although Hartsfield–Jackson Atlanta International Airport is the world's busiest individual airport.

2023 statistics
The following list is based on preliminary full-year figures provided by the Port Authority of New York and New Jersey, along with figures provided by airports and aviation ministries when not available from the former list.

2012 statistics
The following list is based on information provided by the Airports Council International's preliminary full-year figures for the Top 30 airports in the world, and the Top 50 airports in the US.

2010 statistics
The following list is based on two lists compiled by CAPA Centre for Aviation based on data from Airports Council International, one ranking cities with multiple airports and the other ranking individual airports.