Airport by airport: which connections stay inside security, where you need a train or a bus, and where you clear security again.
Connecting at Atlanta (ATL), the world's busiest airport? Once you're through security, every concourse connects behind it, linked by the Plane Train.
Changing planes at Austin (AUS)? Every airline now uses one terminal and all four security checkpoints lead to all gates. Older advice about a separate South Terminal is out of date.
Connecting at Nashville (BNA)? Most gates are a walk apart, but gates C4–C11 are a bus ride across the apron. How to plan it, from a pilot.
Connecting at Boston Logan, Delta's New England hub? Three terminals share one security zone. The fourth needs a shuttle or a second security line — unless you're flying Delta.
Changing planes at Baltimore (BWI)? Concourses A, B and C are one part of the airport, and D and E are another. Going from one part to the other means going through security again.
Connecting at Charlotte (CLT), American's second-largest hub? There are no trains or shuttles here — every gate is reachable on foot from any security checkpoint.
Changing planes at Dallas Love Field (DAL)? The airport has a single terminal with 20 gates and international travel is barred, so connections are domestic. Here is what the airport confirms about security, baggage claim and its airlines, and what it leaves out.
Changing planes at Reagan National (DCA)? Terminal 2 gates share security. Between Terminal 1 (Air Canada, Frontier, Southwest) and Terminal 2, the airport says you go through security again.
Connecting at Denver (DEN)? You never clear security twice, but the train, long concourse walks and the weather decide your margin. A pilot's guide.
Connecting at DFW, American's biggest hub? One train links every terminal behind security, and DFW is piloting a shortcut for some international arrivals.
Connecting at Detroit (DTW)? Delta connections stay in the McNamara Terminal. Switching to Evans means a shuttle and security again. Here's how to plan it.
Connecting at Newark (EWR)? United's airside shuttle links Terminals A and C. Other terminal changes often mean the AirTrain and TSA again. Here's how it works.
Changing planes at Fort Lauderdale (FLL)? Terminals 1, 2 and 3 are not yet joined inside security, so changing between them means going through security again. Here is how to check, and what changes when the new walkways open.
Changing planes at Honolulu (HNL)? The airport lists Hawaiian's check-in in Terminal 1, most other airlines in Terminal 2, and a small island airline in Terminal 3. Here is how the terminals connect and what to check.
Changing planes at Houston Hobby (HOU)? The airport has a single terminal with a Central Concourse and a West Concourse, both reached through the central TSA checkpoint. International arrivals clear immigration and customs in the Federal Inspection Services area. Here is what the airport confirms, and what it leaves out.
Changing planes at Dulles (IAD)? Most gates are in midfield concourses. The AeroTrain serves A, B and C, mobile lounges serve A and D, and a walkway reaches B. Here is what the airport says, and what it leaves out.
Connecting at Houston (IAH), United's Texas hub? There are two separate ways to move between terminals — only one of them stays behind security.
Connecting at New York JFK? Changing terminals means the free AirTrain and a second TSA check. How to plan it, and the Delta Terminal 4 exception.
Changing planes at Las Vegas (LAS)? The airport has two separate terminals with no walkway between them. Here is how to find yours, and what happens if your two flights use different ones.
Connecting at LAX, a hub for four different airlines? A 2023 project connected every terminal behind security, and Terminal 5 is currently closed for a rebuild.
Connecting at LaGuardia (LGA)? Delta is in Terminal C and most other airlines are in B. Switching between them means leaving security. Here's how to plan it.
Changing planes at Orlando (MCO)? The main building is split into two separate security zones, and Terminal C has its own. Two airlines in the same building can still mean going through security again.
Changing planes at Chicago Midway (MDW)? All three concourses are joined inside one security area, so a connection between flights on one ticket is a walk. Here is what to check, and where it gets harder.
Connecting at Miami (MIA)? Only two pairs of concourses — D with E, and H with J — connect without a second security line. Almost everywhere else means clearing security again.
Connecting at Minneapolis-St Paul, Delta's Midwest hub? Its two terminals aren't connected behind security, and the light rail between them takes longer than it looks.
Connecting at Chicago O'Hare (ORD), a dual hub for American and United? Three terminals are an easy walk. The fourth depends on what time your flight lands.
Connecting at Philadelphia, American's Northeast gateway? Every terminal connects behind one security check — the split is about which airline, not about a second screening.
Connecting at Phoenix (PHX)? Most connections stay in one terminal. Switching between Terminals 3 and 4 means the Sky Train and TSA again.
Changing planes at San Diego (SAN)? Terminal 1 and Terminal 2 each have their own security checkpoints, and for now you can't walk between them. Here is how to check your terminal and what a change involves.
Connecting at Seattle (SEA), a hub for Alaska and Delta? Two concourses are reachable only by train, and on an international arrival you collect your checked bags before passport control, even when connecting.
Connecting at SFO, a hub for Alaska and United? Every terminal has connected behind security since 2024, though one route means walking half the loop.
Connecting at Salt Lake City (SLC), Delta's mountain-west hub? Delta mostly flies from Concourse A, other airlines mostly from Concourse B. Check your boarding pass for which concourse you need.
Changing planes at Tampa (TPA)? Each of the four gate buildings has its own security checkpoint, so changing from one to another means going back to the main terminal and through security again.