A power cut at Atlanta’s Hartsfield-Jackson international airport on Sunday led to a partial shut-down, affecting tens of thousands of people.
The airport is the world’s busiest, handling more than 250,000 passengers and almost 2,500 flights every day.
Passengers were left in darkened terminals or on board planes.
Power is now restored at the airport, but over 1,000 flights were cancelled with hundreds more cancellations scheduled for Monday.
Many flights scheduled to arrive from other airports were being diverted elsewhere or held at their departure airport.