Phoenix Sky Harbor International Airport is a civil-military public international airport 3 mi east of downtown Phoenix, in Maricopa County, Arizona, United States. It is Arizona's largest and busiest airport; among the largest commercial airports in the United States, PHX was the 8th-busiest airport in the United States and 22nd-busiest in the world in 2…Phoenix Sky Harbor International Airport is a civil-military public international airport 3 mi east of downtown Phoenix, in Maricopa County, Arizona, United States. It is Arizona's largest and busiest airport; among the largest commercial airports in the United States, PHX was the 8th-busiest airport in the United States and 22nd-busiest in the world in 2021. The airport serves as a hub for American Airlines and a base for Frontier Airlines and Southwest Airlines.