Connecting in Canada to a US flight: how US preclearance works

If you're connecting at a large Canadian airport to a flight to the United States, you clear US customs and immigration in Canada, before you board. It's called preclearance: US Customs and Border Protection (CBP) officers work at the Canadian airport. You land in the US as a domestic passenger, with no customs, no bag recheck and no TSA line on arrival, so a connection at your US airport is much simpler. The trade-off is that the US checks happen during your layover in Canada, so you need time for them there.

Where preclearance exists

CBP runs preclearance at 16 locations. In Canada: Calgary, Edmonton, Halifax, Montréal-Trudeau, Ottawa, Toronto Pearson, Billy Bishop Toronto City, Vancouver, Victoria and Winnipeg. Outside Canada: Dublin and Shannon in Ireland, Aruba, Bermuda, Nassau in the Bahamas and Abu Dhabi.

Connecting through Canada to the US, step by step

1. Follow the signs for connections to the United States when you get off your first flight. Don't follow the exit signs.
2. Security screening for the US connection. When you arrive in Canada from an international flight, you and your bags are re-screened in the US connection area.
3. US preclearance. A CBP officer checks your documents and admissibility, just as they would at a US airport. Biometric information may be collected.
4. Go to your gate. You're now in the US-bound area, and when you land in the US you walk out like a domestic passenger or go straight to your next flight.

If you're flying from within Canada, you'll also clear preclearance at the Canadian airport before your US flight.

Rules on checked bags vary with how you booked and the route, so check your bag tags and ask your airline whether bags go through to your final destination.

How much time to leave

Neither CBP nor the Canadian government publishes a standard connection time for preclearance. Plan for:

• Lines at preclearance, which vary by time of day and how many US flights are leaving.
• Security screening in the US connection area.
• Walking between the arrival gate and the US departure area.

On one ticket, the airline sold you a connection it considers long enough and must rebook you if you miss it. On separate tickets, leave much more time. Read is a 1-hour layover enough?

Ways to speed it up

• Mobile Passport Control. CBP is installing its free app's processing at Canada's preclearance airports. Eligible travelers (US citizens and permanent residents, Canadian visitors, and returning Visa Waiver Program travelers with ESTA) can submit their information ahead of time where it's available.
• Trusted traveler programs such as Global Entry speed up the US check for members.

Your rights in preclearance

Signs at the preclearance area explain your obligations and your right to withdraw. Under Canadian law, you can withdraw from preclearance and leave the area without flying to the US, but you must answer the officer's questions about who you are and why you're withdrawing.

Connecting between two international flights in Canada

Not going to the US? Since June 2026, if you connect between two international flights at Vancouver, Montréal-Trudeau or Toronto Pearson Terminal 1, the Canada Border Services Agency's Free Flow process lets you go straight to the international departure area without seeing a border officer. Conditions include a confirmed onward international flight within 24 hours and the right travel documents. If your bags aren't transferred automatically, or your flight isn't the same day, you collect your bags and go through the usual arrival process.

Do you need an eTA or visa to transit Canada?

Passengers transiting Canada by air need an eTA or a visa, whatever the length of the stay, unless an exception applies. Some travellers flying through Canada to or from the United States can use Canada's Transit Without Visa Program if they hold a valid US visa and leave for the US within 24 hours.

Keep an eye on your first flight

Add both flights to FlyingOver before you travel. You can follow the first flight offline and see its estimated arrival, so you know early how much time you'll have for preclearance.