The U.S. Transportation Department said on Thursday that airlines carried 3.4 percent more passengers on U.S. domestic and international flights in 2017 for an all-time high of 965 million passengers.

The government said international travel rose 4.8 percent in 2017 to 223.4 million passengers, also a record, and foreign airlines carried 6.1 percent more passengers last year on U.S.-bound and departing flights. Carriers transported 741.6 million passengers on U.S. domestic flights in 2017, up 3 percent.

Southwest Airlines Co led all carriers again with 157.7 million passengers on U.S. flights, up 3.9 percent, followed by Delta Air Lines Inc , which rose to second with 145.6 million passengers, up 1.8 percent, followed by American Airlines Group Inc with 144.9 million.

United Air Lines , despite a controversy involving a passenger dragged out of his seat at Chicago's O'Hare Airport in April 2017, reported a 7.1 percent increase to 107.2 million passengers. The four largest U.S. carriers accounted for 58 percent of total passengers in 2017.

Among U.S. airports, Atlanta remained the busiest airport in 2017, handling 50.2 million passengers, down 0.5 percent, followed by Los Angeles with 41.2 million. Denver edged out New York's JFK airport for fifth busiest airport in 2017 with 29.8 million passengers. JFK remained the busiest U.S. airport for international travelers.