New York JFK-Los Angeles was the most heavily flown U.S. domestic route of 2025, according to an analysis by aviation data company OAG.
Airlines will offer 3.43 million seats between JFK and LAX this year, up 9% from 2024 though still 20% below 2019.
New York LaGuardia-Chicago O'Hare was the second-biggest domestic route, followed by LAX-San Francisco, LAX-Las Vegas, Atlanta-Orlando, Denver-Phoenix, Honolulu-Maui (Kahului), LAX-O'Hare, Atlanta-LaGuardia and Atlanta-Fort Lauderdale.
Carriers will fly 3.33 million seats between LaGuardia and O'Hare, up 7% from last year, but 13% below 2019. On LAX-San Francisco, carriers will offer 3.31 million seats this year, up 5% year over year but down 29% from 2019.
Significant drawbacks from American and JetBlue since pre-pandemic highs have shrunk JFK-LAX, OAG senior analyst John Grant said. Meanwhile, substantial drawbacks from American and Delta on LaGuardia-O'Hare have dwarfed United's service increase on that route. And capacity cuts since 2019 of at least 40% by Alaska, Southwest and American in the LAX-San Francisco market have driven the drawback on that city pair.
Grant said that along with diminished corporate demand, better capacity discipline by airlines appears to have led to the cutbacks.
The biggest cross-border route involving the U.S. was New York JFK-London Heathrow. Airlines will fly 3.97 million seats between JFK and Heathrow this year, down 1% from 2024. That seat count makes JFK-Heathrow the 10th most flown cross-border route in the world. The leader is Hong Kong-Taipei with 6.83 million seats.
Globally, the puddle-jumping South Korean domestic route between Seoul and Jeju Island remains the world's busiest, with 14.38 million scheduled seats this year, or almost 39,000 per day.