More than 900 million people passed through TSA checkpoints in 2025, setting a new record for U.S. air travel. Wondering which flights were most popular with passengers? As you might expect, many of America’s largest cities and busiest airline hubs feature in the top 10, but there were a few surprising city pairings, too. Discover the 10 busiest U.S. domestic flight routes last year, according to data compiled by the Official Airline Guide (OAG) and ranked by airline seat capacity.

10. Atlanta to Fort Lauderdale

Number of seats in 2025: 2,631,730

Fort Lauderdale might be only the 150th-biggest city in the U.S., but the Sunshine State is a perennially popular vacation destination, and Fort Lauderdale-Hollywood International Airport serves as a gateway to the broader South Florida region. Many of those vacationers routed through Hartsfield-Jackson Atlanta International Airport, which has held the title of the world’s busiest airport for 27 out of the past 28 years. In 2025, over 105 million passengers passed through the airport.

9. Atlanta to New York (LaGuardia)

Number of seats in 2025: 2,763,776

On a typical day, there are around two dozen flights between Atlanta and New York’s LaGuardia Airport on three airlines: American, Frontier, and Delta. You also can fly from Atlanta to New York’s JFK Airport, Newark Airport in New Jersey, or White Plains in Westchester County.

8. Los Angeles to Chicago (O’Hare)

Number of seats in 2025: 2,793,178

Both LAX and O’Hare are hubs for American and United, and the two airlines move a lot of passengers between these airports. In 2026, Delta joined in on the action, while Southwest offers flights from LAX to Midway, Chicago’s other major airport. 

7. Honolulu to Kahului

Number of seats in 2025: 3,045,165

This route may be surprising to see in the top 10, but because air travel is the only efficient way for Hawaiians (and tourists) to travel between islands, it sees a huge volume of traffic each year. In fact, in 2023 it ranked as the No. 1 busiest route in the country. Today, there are around 30 daily departures between Honolulu, on the island of Oahu, and Kahului, located on Maui. Only 100 miles separate the two cities, which means the flight lasts around 30 minutes.

6. Denver to Phoenix

Number of seats in 2025: 3,118,880

Denver is home to one of the country’s fastest-growing airports, jumping from No. 23 globally in 2019 to No. 6 in 2023, according to OAG. The biggest destination from DIA in terms of airline seat capacity is Phoenix Sky Harbor International Airport, which offered over 3 million seats in 2025.

5. Atlanta to Orlando

Number of seats in 2025: 3,226,190

The busiest route from the world’s busiest airport is Atlanta to Orlando. Thousands of travelers head to the land of Disney and other theme parks each day, and they have around two dozen daily flights to choose from on Delta, Frontier, and Southwest Airlines. 

4. Las Vegas to Los Angeles

Number of seats in 2025: 3,283,510

It’s around a four- to five-hour drive between L.A. and Vegas, but many travelers opt for the quick one-hour flight instead. They’re spoiled with choice: American, Delta, Frontier, Southwest, and United all serve this route, and there are even more options between Vegas and other L.A.-area airports such as Burbank, Long Beach, and Ontario. 

3. Los Angeles to San Francisco

Number of seats in 2025: 3,306,223

Millions of people still travel between California’s two biggest cities each year, but traffic is down compared with pre-pandemic levels. While the LAX-to-SFO route ranks as the third-busiest in the country, there were 29% fewer seats available in 2025 than in 2019, according to OAG.

2. New York (LaGuardia) to Chicago (O’Hare)

Number of seats in 2025: 3,334,011

This busy route has multiple flights an hour on American, Delta, and United. As with flights between L.A. and San Francisco, traffic still lags behind pre-pandemic levels (13% lower), but it’s on the rebound — seats increased 7% between 2024 and 2025. 

1. New York (JFK) to Los Angeles

Number of seats in 2025: 3,431,159

Perhaps it’s no surprise to see the route connecting America’s two largest cities in first place on the list of the top 10 busiest flights. New York to L.A. is one of the country’s most lucrative markets for airlines, who compete for high-end business travelers with amenities like lie-flat beds and fancy lounges. American was the first to launch coast-to-coast jet service in 1959 aboard the Boeing 707. Today the route is also served by JetBlue and Delta, while Alaska and United passengers can fly from Newark to LAX. 

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