Main US Airports: How the FAA Defines Major Hubs

Searching for the main US airports sounds like a request for one definitive list. The official answer is more useful: the Federal Aviation Administration, or FAA, classifies US airports by activity and by each airport's share of national commercial passenger boardings. Those categories can change as traffic changes, so a frozen ranking soon loses value.

This guide explains the FAA framework, what it can and cannot tell you, and how to turn it into a practical choice for a flight. It does not rank airports by comfort, punctuality or quality. Those are different questions, and an airport's hub category does not answer them.

What counts as a main US airport?

In everyday travel language, “main airport” often means the airport with extensive scheduled service in a city or region. The FAA uses more exact terms. A primary airport is a commercial-service airport with more than 10,000 passenger boardings in a year. A passenger boarding is also called an enplanement.

Primary airports are then grouped as large hub, medium hub, small hub or nonhub. “Hub” here is a statutory traffic category. It describes an airport's portion of annual US commercial enplanements; it does not promise that every airline treats that airport as a connecting hub.

FAA category	Share of annual US commercial boardings	What the label means
Large hub	1 percent or more	A primary airport with the largest national passenger share.
Medium hub	At least 0.25 percent and under 1 percent	A primary airport with a substantial national passenger share.
Small hub	At least 0.05 percent and under 0.25 percent	A primary airport with a smaller national passenger share.
Nonhub primary	Under 0.05 percent and more than 10,000 boardings	A primary airport below the small-hub share.

The FAA also defines nonprimary commercial-service, reliever and general aviation airports. That matters because the United States has far more aviation facilities than the large passenger terminals most travelers picture. The FAA National Plan of Integrated Airport Systems, known as NPIAS, identifies nearly 3,300 public-use airports in the national system and describes the roles they serve.

Why there is no permanent “top airports” list

The FAA publishes passenger boarding data collected for a full calendar year and uses it to calculate airport categories and funding entitlements for a later fiscal year. In other words, the classification follows measured activity. An airport can move between categories as its portion of national boardings changes.

That is why this guide does not turn a current data table into an evergreen claim that certain airports will always be the main ones. If you need the current order, use the FAA's Passenger Boarding and All-Cargo Data page. It provides official rank-order material and explains which calendar-year data feed which classification cycle.

The distinction also prevents a common planning mistake: assuming that a busier category automatically means a better airport for a particular trip. A large hub can offer many routes but may involve multiple terminals, trains or long walks. A smaller primary airport may be simpler, but it may offer fewer nonstop choices. Confirm the actual itinerary rather than selecting by category alone.

How to choose between airports in the same region

When a city has more than one passenger airport, begin with the flight itself. Check whether the route is nonstop, whether a connection is on one ticket, and which terminal the operating airline uses. Then open the official airport map and trace the path from arrival to the next gate, baggage claim or ground transportation.

1. Compare the whole itinerary. Look past the airport code and examine connections, terminal changes and the operating carrier.
2. Check the official terminal map. Save it before travel. The airport operator is the authority for terminal roads, checkpoints and inter-terminal transport.
3. Read the airline's instructions. Baggage and check-in rules belong to the airline, while screening rules belong to TSA.
4. Plan the ground journey. Compare where each airport sits relative to your real destination, not merely the city name in the search result.
5. Recheck before departure. Gates, procedures and airport services can change.

An airport code is the cleanest way to distinguish similarly named facilities. Keep the code with the terminal name in your notes and boarding-pass screenshot. For a wider geographic view, use the United States airport map; for the practical terminal routine, read how to navigate an airport.

What the FAA category does not tell you

A hub label is not a terminal guide. It does not identify your gate, tell you whether you must change terminals, establish an airline's baggage cutoff, or measure the journey from downtown. It also does not replace an airport's own accessibility, parking or ground-transport information.

The FAA says its airport programs support a safe, efficient and environmentally responsible national airport system. Its air traffic organization also operates across a network far larger than any single terminal, handling 44,360 flights on an average day according to the agency's published overview. These system facts provide context, but they do not predict the conditions for your individual flight.

Security rules at main airports

Large and small US passenger airports operate within TSA's layered screening system. TSA says checkpoint procedures are designed to keep prohibited items and other threats out of the sterile area—the secure part of the terminal beyond screening. The agency can adjust procedures as threats evolve, so the process may not look identical on every trip.

For carry-on liquids, follow the TSA 3-1-1 rule: liquids, aerosols, gels, creams and pastes must be in containers of 3.4 ounces or 100 milliliters or less, placed in a quart-sized bag. TSA says larger containers should go in checked baggage, subject to applicable rules and exemptions. An item that alarms may require additional screening even when the item is normally permitted.

TSA's What Can I Bring? tool is the official place to check a specific object. Its guidance also warns that a generally permitted item can face extra screening or be refused if it alarms, appears tampered with or creates another security concern. For a packing-focused explanation, see what you can bring on a plane.

A calm routine for a major US airport

Busy terminals become easier when the essential information is already on your phone. Save the boarding pass, airport code, terminal, gate area and official map for offline use. If you are connecting, save the arrival and departure terminals together so you can see the transfer at a glance.

At the airport, read the current flight display before following a saved gate. Follow official signs for departures, connections, baggage claim or ground transportation. If instructions conflict, ask the airline or airport staff responsible for that part of the journey.

Keep screening items organized and use TSA's official page for anything unusual. The agency reports screening approximately 3.3 million carry-on bags each day, and its procedures may include additional checks. Packing so you can reach documents and permitted liquids without unpacking everything makes your own checkpoint routine clearer.

The useful answer to “which are the main airports in the USA?”

Use FAA categories to understand national scale, then use live route and terminal information to make a travel decision. Large hubs sit at the top of the FAA passenger-share framework; medium, small and nonhub primary airports remain important parts of scheduled US air travel. NPIAS places those commercial airports within a much broader national system.

For a current list, check the FAA passenger boarding dataset rather than an undated roundup. For the trip itself, trust the airport operator for maps and facilities, the airline for its itinerary and baggage terms, and TSA for checkpoint rules. Rules and operations change, so confirm each official source before flying.