When I fly, I love clearing customs in advance. That is, I love having my passport checked by U.S. Customs and Border Protection officers before I ever get on the plane, which lets me avoid waiting in line when I land.

Although I have Global Entry, which speeds up my arrival into the United States from abroad, it’s even better when I can go through all the border formalities before getting on the plane. That way, I can just breeze off and get home without waiting in a long line in the bowels of JFK Airport.

Customs preclearance for U.S.-bound flights is available – or really, required – at a handful of airports around the world. I’ve mostly experienced it returning from trips to Canada, where U.S.-bound flights are usually segregated into their own section of the airport terminals.

Here’s what you need to know if you’re flying back from a country with U.S. customs before the plane.

What is customs preclearance?

Put simply, customs preclearance is U.S. border screening that takes place in another country, before passengers board their flights bound for a U.S. airport.

“There are U.S. Customs and Border Protection personnel there and once we clear it, when we land, we land as if we are a domestic flight,” Sheldon Jacobson, professor of computer science at the University of Illinois’ Grainger College of Engineering, told me. “For travelers, once they clear customs in another country, they basically are in the United States already once they board their plane.”

According to Customs and Border Protection, 22 million travelers passed through preclearance facilities in 2024, representing 16% of inbound commercial airline passengers that year.

Where are there customs preclearance facilities?

CBP has preclearance facilities at 15 airports abroad:

Canada

• Calgary
• Edmonton
• Halifax
• Montreal
• Ottawa
• Toronto
• Vancouver
• Victoria
• Winnipeg

Caribbean

• Aruba
• Bahamas (Nassau)
• Bermuda

Ireland

• Dublin
• Shannon

United Arab Emirates

• Abu Dhabi

All preclearance facilities except Victoria, British Columbia, have Global Entry kiosks as well.

What are the benefits to customs preclearance?

Clearing customs before boarding a flight can make it easier for passengers to make tight connections, and just generally makes the arrival process easier.

According to CBP, preclearance lets passengers make tighter connections in the United States, and they can avoid rechecking their bags and having to go through security screening again after arriving in the United States.

“It makes our lives a little easier, especially if we have a connecting flight, because it’s treated as a domestic flight on the return,” Loulu Lima, founder of the Texas-based travel agency Book Here Give Here, told me. “This is a well-oiled machine.”

Preclearance also reduces the pressure on customs facilities at U.S. airports. Imagine how much longer border control lines would be if 22 million more passengers needed to be processed on arrival into the United States every year.

For travelers departing from airports with preclearance facilities, it’s especially important to leave extra time before your flight. While the facilities are usually efficient, you’ll need to clear both airport security and customs before proceeding to your gate.

Jacobson added that customs preclearance also has a security benefit, giving airlines more operational flexibility to serve smaller airports that don’t have customs facilities of their own.

“If you’re screening people in the United States and they can’t enter, you have them in this state of limbo,” he said. “You’ve added another layer of security screening by adding the clearance before they get on the airplane.”

If a traveler gets denied entry into the United States at a customs facility abroad, they don’t have to be transported back to the country of origin.

Is the program going to expand?

Jacobson said he thinks the program will expand slowly over time but acknowledged it’s not always easy to set up a new preclearance checkpoint.

“I believe it’s going to expand. It’s a question, of course, of getting the officers in place,” he said. “It’s a question of the footprint that they're going to have available to them. Once you get past the screening for border protection, you are entering the United States. ... It has to be done with care, because if you don’t, you’re potentially letting people into the country who you shouldn’t.”

Still, he added, airports abroad with high volumes of passengers departing to the United States, like London, Paris and Rome, could be good candidates for these kinds of facilities in the future.

“It’s not trivial to implement, but the benefits for the travelers, for the airlines, are tremendous,” he said.