Connecting Flights in the USA ▷ What You Need to Know

In a nutshell

A connecting flight in the USA is more involved than transiting in Europe or Asia — you always have to go through full immigration, no matter how short your layover.
With the right prep, though, it’s totally manageable. You’ll need an ESTA (or visa) and we strongly recommend the free MPC App to cut your wait at immigration.
We’ll walk you through exactly what to prepare, how the transit process works on the ground, and share our best tips for getting through the airport as fast as possible.

What Do You Need to Know About a Layover in the USA?

Many affordable flight connections to Mexico, Ecuador, Chile, and other destinations in Central America and South America route through the USA.

If you’re booking a flight with a US connection, there’s one thing you really need to know upfront: transiting in the USA works very differently from most transit airports in Europe and Asia.

You’re officially required to enter the country — no matter how short your layover is. That means you absolutely need an ESTA or a visa. To avoid long waits at immigration, we strongly recommend the MPC App — it cuts your wait time significantly. We’ll walk you through both in just a moment.

You’ll also need to collect your luggage at the US transit airport, re-check it, and go through security again.

How Much Time Should You Allow for Your Layover in the USA?

Moving walkway at Washington Airport — Airports in the USA are usually very large — make sure to allow plenty of time for getting around (© martince2)

All of this takes quite a bit of time.

To make sure you catch your connecting flight, there’s an MCT (Minimum Connection Time) — a calculated minimum buffer built into combined flight bookings. Flights with a connection time shorter than the MCT won’t show up on Skyscanner and similar sites, so under normal circumstances you should make your second flight.

That said, delays and other hiccups can always happen. That’s why we recommend building in more buffer than just the MCT.

How much time you actually need depends mainly on your first flight — specifically, whether you have to go through immigration or not:

Stopover without entry (your first flight is a domestic US flight): 1–1.5 hours
Stopover with entry (both flights are international): at least 2–3 hours

When we connected from Frankfurt to Mexico City through Dallas, immigration took us just under an hour. On the return from Cancún to Frankfurt via Charlotte, it was about 45 minutes. The first trip went smoothly with no waiting at all; on the second, the MPC App saved us a solid chunk of time in line.

Even with a generous buffer, you can still miss your connecting flight — that’s not uncommon in the USA. But if it happens, staff will simply rebook you for free onto the next flight to your destination.

Preparing for Your Layover in the USA

Applying for an ESTA for Your USA Transit

You also need to factor in the cost of an ESTA — You absolutely need an ESTA or a visa for a transit through the USA

At least 72 hours before entry

For your US layover, you must apply for an ESTA — even if your connection is very short. The USA has no sterile transit area. You always have to formally enter the country, and for that you need authorization.

You apply for the ESTA for around $40 online at the U.S. Customs and Border Protection website or through their app (iOS | Android). Approval can take anywhere from a few minutes to several hours.

Important: Only apply through the official website or the app — never through third-party providers. Those are scam sites.

In our article about entering the USA, we explain in more detail how to apply for your ESTA.

ESTA or Visa?

If you have no criminal record and have never traveled to a country the USA considers high-risk, you can typically apply for an ESTA.

However, if you’ve traveled to Cuba after 2021, for example, you’ll need to apply for a visa instead. We cover how to do that in our article on entering the USA.

The key thing: apply for your visa several weeks before your trip, since it’s a much more involved process than the ESTA.

Filling Out the MPC App

Can be done up to shortly before departure (takes about 5–10 minutes)

The MPC App (iOS | Android) is the free Mobile Passport Control app from the US border authority.

Through the app, you can submit your entry information and customs declaration in advance. You can enter the data for everyone in your travel group in a single app — only one person needs to have it installed. With the app, you get access to a dedicated line at immigration with a significantly shorter wait.

Unfortunately, the MPC App is not available at all airports. You can check in advance on the U.S. Customs and Border Protection website or directly in the app whether your airport is supported.

Getting Your Transfer Bag Luggage Tag

Pick up at your departure airport

Your luggage is tagged with your final destination at your departure airport. When transiting through the USA, though, you’ll usually still need to collect it and re-check it.

The exception is currently the airports in Atlanta (ATL), Dallas (DFW), Houston (IAH), and Miami (MIA) when you’re flying with United Airlines or a Oneworld Alliance carrier like American Airlines.

At these four airports, there are red luggage tags labeled “Transfer Bag Outside U.S.A.” that allow your bag to be transferred directly at the transit airport. You don’t need to pick it up or re-check it — which saves you a real chunk of time.

We got our tag from a friendly American Airlines employee at Frankfurt Airport who was stationed at the self-check-in kiosks.

The airports and airlines where the Transfer Bag luggage tag is available may change. Always ask at your departure airport whether the tag is available for your flight.

What to Expect During Your USA Transit

Be especially polite during US border control — Connecting through the USA works a little differently than at other transit airports

Submitting Your Documents in the MPC App

Submitting documents in the MPC app — Tap on the blue button

MPC App confirmation — The confirmation is valid for 4 hours

Once you arrive at the transit airport and connect to the airport’s Wi-Fi, submit your documents through the MPC App. You’ll take a selfie of each person in your travel group within the app, then submit everything.

You’ll receive a confirmation that is valid for four hours from that point.

With the MPC App, you’re allowed to use a separate line at immigration. Follow the signs marked MPC and show your confirmation to the staff member there.

Immigration

At immigration, your passport and ESTA will be checked. Your fingerprints and a photo will be taken, and you’ll be asked a few questions.

If you’re just passing through the USA, these are typically three short questions:

What is the purpose of your visit?: Explain that you’re in transit.
What is your final destination?: Name the city you’re ultimately headed to.
When does the plane leave? / How long will you be in transit?: Answer with your scheduled departure time or give a rough estimate in hours.

Baggage Claim and Customs

Police officer at the baggage carousel at Atlanta Airport — If you had a longer wait at immigration, your bag is probably already waiting on the baggage carousel (© Koapan)

The baggage carousels are right after immigration.

When connecting through the USA, your luggage is often already there by the time you’re done with immigration. If not, you’ll have to wait a bit.

After that, you take your bag through customs and re-check it. A staff member will meet you, scan your luggage tag, and tell you where to drop off your bag.

You can skip this step if you’re connecting through Atlanta, Dallas, Houston, or Miami and have the red Transfer Bag Outside U.S.A. luggage tag.

Security Check

Finally, you’ll go through security one more time.

After that, you can head to your gate. You may need to change terminals after the security check to get there — find out in advance how to get between terminals. In Dallas, for example, we took the free Skylink train two terminals over.

Tips for Shorter Wait Times

Download the MPC App and use it to submit your entry documents in advance. This lets you skip the regular line at immigration.
On your first flight, try to book seats as far forward as possible. You’ll get off the plane faster and be among the first in line at immigration.
Download the offline map of the airport on Google Maps before you fly. You can then access it quickly even without Wi-Fi to see exactly where you need to go. Our article on trip planning with Google Maps shows you how.
Make sure your checked and carry-on luggage doesn’t contain anything that’s allowed at your destination but not in the USA.
Pick up a Transfer Bag tag if you’re connecting through Atlanta, Dallas, Houston, or Miami — then you won’t have to worry about your luggage during the transit at all. Just ask a staff member at check-in.
Always stay polite and friendly and avoid arguments. They only cost you time.

Connecting Through the USA with Kids

Child with suitcase — Transiting through the USA with kids follows a similar process to traveling without them

The process for connecting through the USA with kids is basically the same. There are just a few extra things to keep in mind:

Plan for a more generous connection time. Two hours is the absolute minimum when traveling with children.
Every child needs their own ESTA. Babies and toddlers also have to go through immigration. You often can’t rely on the electronic systems when traveling with kids, so the MPC App advantage may not apply.
Checked strollers sometimes make it to the gate, but sometimes you’ll need to pick them up at baggage claim — it varies by airport.
Baby food, milk, and special drinks for children are allowed through security. You’ll just need to present them separately at the checkpoint.