There are 672 airports in the US with scheduled commercial services, but the country’s ten busiest airports account for around 35% of all flights. With demand for air travel increasing around 2% in 2025 compared to 2024, airports across the country are busier than ever, but there is one in particular that is far busier than all the rest.
In this article, we will use data from OAG to take a look at which airports across the US ranked as the country’s busiest by number of seats available in summer 2025. For each of the airports, we will also consider their most popular routes and any airlines that call the facility home.
10
Seattle-Tacoma International Airport
19.6 million seats
In summer 2025, there were just over 19.6 million seats available from Seattle-Tacoma International Airport (SEA), making it the busiest airport in the Pacific Northwest and the third-busiest on the West Coast. The facility serves as a major hub for both 
Alaska Airlines and Delta Air Lines, with the two carriers commanding a 51% and 24% market share, respectively.
This puts them way ahead of third-placed United Airlines, with just 5%. Although the breakdown of seats for summer 2025 is yet to be released, the most popular destinations from 
Seattle-Tacoma International Airport over the past 12 months are detailed in the table below.
|
Ranking |
Destination |
Number Of Passengers |
|---|---|---|
|
1 |
Los Angeles International Airport (LAX) |
961,000 |
|
2 |
Ted Stevens Anchorage International Airport (ANC) |
960,000 |
|
3 |
Phoenix Sky Harbor International Airport (PHX) |
935,000 |
|
4 |
Denver International Airport (DEN) |
924,000 |
|
5 |
Harry Reid Las Vegas International Airport (LAS) |
905,000 |
Seattle-Tacoma International Airport is one of Delta Air Lines’ primary transpacific hubs, with the SkyTeam carrier offering flights to a wide variety of destinations. These include Seoul Incheon International Airport (ICN), Shanghai Pudong International (PVG), Taipei Taoyuan International (TPE), and Tokyo Haneda (HND).
9
San Francisco International Airport
19.6 million seats
For the whole of 2024, San Francisco International Airport (SFO) was the 13th-busiest airport in the US, but for summer 2025, the facility rose to ninth place, with more than 19.6 million seats available. The airport is one of the largest hubs for United Airlines, with the 
Star Alliance carrier accounting for just under 50% of all flights.
Last year, the busiest domestic route from San Francisco International Airport was to Los Angeles International Airport (LAX), with a total of 1,356,000 passengers. When it comes to international services, the three busiest destinations were Taipei Taoyuan International Airport (TPE), London Heathrow (LHR), and Vancouver International (YVR). These three routes saw 1,357,000 passengers, 1,041,000 passengers, and 816,000 passengers, respectively.
8
Charlotte Douglas International Airport
20.1 million seats
The eighth-busiest airport in the US in summer 2025 was Charlotte Douglas International Airport (CLT), with a total of 20.1 million seats available. The airport is one of the primary hubs for 
American Airlines, and the oneworld carrier dominates operations, with a 70% market share.
The bulk of American Airlines’ operations at Charlotte Douglas International Airport are domestic services, with the most popular routes being to Orlando International Airport (MCO), LaGuardia Airport (LGA), and Dallas/Fort Worth International Airport (DFW). However, the carrier also serves a number of international destinations across the Americas and Europe, including 
London Heathrow Airport (LHR), Madrid Barajas Airport (MAD), and Punta Cana International Airport (PUJ).
These Are American Airlines’ Leading Hubs By Passenger Numbers
American Airlines has around a 60-70% market share at Dallas/Fort Worth, Charlotte, and Miami airports.
7
Harry Reid International Airport
20.3 million seats
The seventh-busiest airport in the US in summer 2025 was Las Vegas’ Harry Reid International Airport (LAS), with more than 20.3 million seats available. Southwest Airlines is the largest carrier at the airport, commanding a market share of more than 40%, while other carriers with a significant presence include Spirit Airlines, Delta Air Lines, American Airlines, and Frontier Airlines.
In total, Las Vegas Harry Reid International Airport saw more than 58 million passengers in 2024, which was its highest passenger figure recorded, far surpassing its pre-pandemic peak of 51 million passengers in 2019. With more than 20.3 million seats available in the peak summer period alone, it is expected that the airport will see in excess of 58 million passengers overall this year.
6
John F. Kennedy International Airport
23.6 million seats
John F. Kennedy International Airport (JFK) is one of the most iconic airports in the US, and is one of the country’s primary international gateways, attracting carriers from all over the world. This is highlighted in the number of international carriers that appear in the list of the largest airlines to operate at the facility, including Virgin Atlantic and 
Emirates.
|
Ranking |
Airline |
Market Share |
|---|---|---|
|
1 |
Delta Air Lines |
29.7% |
|
2 |
JetBlue |
23.4% |
|
3 |
American Airlines |
11.8% |
|
4 |
British Airways |
2.1% |
|
5 |
avianca |
1.9% |
|
6 |
Alaska Airlines |
1.8% |
|
7 |
Virgin Atlantic |
1.7% |
|
8 |
Air France |
1.6% |
|
9 |
Frontier Airlines |
1.6% |
|
10 |
Emirates |
1.4% |
New York-JFK Airport also plays host to what is currently the world’s longest nonstop commercial flight. 
Singapore Airlines operates daily nonstop services between the facility and its hub at Singapore Changi Airport (SIN) with its specially-configured Airbus A350-900ULR aircraft.
5
Los Angeles International Airport
27.1 million seats
The fifth-busiest airport in the US in summer 2025 was Los Angeles International Airport (LAX), with 27.1 million seats available. This makes it the third, and largest, West Coast hub to feature in this list. All three of the major US legacy carriers have a significant presence at Los Angeles International Airport. Indeed, 
Delta Air Lines (18.9%), United Airlines (15.8%), and American Airlines (15.3%), all operate several high-profile long-haul routes from the hub.
The busiest international route from Los Angeles International Airport last year was to London Heathrow (LHR), with more than 1.6 million passengers. Four different airlines deploy their widebody aircraft between the two cities: American Airlines, British Airways, 
United Airlines, and Virgin Atlantic. The second-busiest international destination was Seoul Incheon International Airport (ICN), followed by Guadalajara International (GDL).
The Busiest Airports In California In 2025
Los Angeles International Airport is the busiest airport in California by scheduled departures.
4
Denver International Airport
29.7 million seats
The fourth-busiest US airport in summer 2025 was Denver International Airport (DEN), which had more than 29.7 million seats available. The airport serves as a primary hub for United Airlines, which is by far the largest operator, with a 49% market share, followed by 
Southwest Airlines with 29%.
The busiest domestic destinations from the airport are Phoenix Sky Harbor International Airport (PHX), Chicago O’Hare International Airport (ORD), and Harry Reid International Airport (LAS), each of which saw in excess of one million passengers last year. The airport’s busiest international routes are detailed in the table below.
|
Ranking |
Destination |
Passengers |
|---|---|---|
|
1 |
Cancun International Airport (CUN) |
545,000 |
|
2 |
Vancouver International Airport (YVR) |
423,000 |
|
3 |
London Heathrow Airport (LHR) |
413,000 |
|
4 |
Frankfurt Airport (FRA) |
327,000 |
|
5 |
Munich Airport (MUC) |
300,000 |
One of Denver International Airport’s runways, 16R/34L, is the longest commercial runway in the US, and the seventh-longest in the world, measuring 3.03 miles (4.88 km) long. In 2024, the airport set a record, processing more than 82 million passengers in total, significantly higher than its pre-pandemic peak of 69 million passengers in 2019.
3
Dallas/Fort Worth International Airport
30.7 million seats
Dallas/Fort Worth International Airport (DFW) was the third-busiest airport in the US in summer 2025, with more than 30.7 million seats available. The airport serves as American Airlines’ largest hub, with the oneworld carrier commanding a market share of over 66%.
The vast majority of the busiest routes from Dallas/Fort Worth International Airport are to destinations across North America. However, long-haul routes to London Heathrow Airport (LHR), Madrid Barajas (MAD), and Seoul Incheon International (ICN) also made the top ten last year. 2024 was the busiest year on record for the airport, with more than 84 million passengers, and 2025 looks set to be even busier again.
2
Chicago O’Hare International Airport
31.3 million seats
The second-busiest airport in the US in summer 2025 was Chicago O’Hare International Airport (ORD), which had in excess of 31.3 million seats available. The airport is a hub for both American Airlines and United Airlines, with the latter offering flights to destinations across Europe, South America, and Asia. Its destinations on this front include São Paulo Guarulhos International (GRU), Tokyo Haneda (HND), Frankfurt (FRA), and 
Charles de Gaulle Airport (CDG).
Chicago O’Hare International Airport is one of the few major US airports that has yet to beat its pre-pandemic peak when it comes to total passenger numbers. In 2019, the airport processed a record-breaking 84.6 million passengers, while in 2024, the number had reached just 80.0 million. It remains to be seen if the airport will surpass this figure in 2025.
The Busiest Airports In The World In 2025
Here are the six busiest airports of the year so far, and a look at how the list has changed from 2024.
1
Hartsfield–Jackson Atlanta International Airport
38.1 million seats
The busiest airport in the US in summer 2025 was 
Hartsfield–Jackson Atlanta International Airport(ATL), with more than 38.1 million seats available. This should come as no surprise, given that the facility has been consistently crowned the world’s busiest airport in recent years, processing more than 108 million passengers in 2024.
Delta Air Lines is by far the largest carrier at Hartsfield-Jackson Atlanta International Airport, with the SkyTeam airline commanding a 74% market share. The facility serves as the largest hub for Delta Air Lines, and the carrier offers flights to long-haul destinations across the world, including as far away as Johannesburg OR Tambo International Airport (JNB). The airport also sees services from several international carriers, including Ethiopian Airlines, Virgin Atlantic, and Turkish Airlines.
