Who can use the Preclearance Program before entering the US?

Before US travelers are allowed to enter their final destination, the United States, every passenger is normally checked by US border officials after leaving the aircraft. These entry and customs checks traditionally only take place after arrival in the USA on American soil. The Preclearance program, however, allows these border controls for travelers and their baggage to take place before boarding the aircraft at the foreign airport of departure.

Special CBP border control zones were opened at the participating airports to facilitate these Preclearance checks. Preclearance border control is no different from the classic US border control upon arrival in the United States. However, travelers who have been pre-checked by Preclearance do not have to undergo the usual check upon arrival in the United States.

Toronto Pearson Airport was inaugurated in 1952 as the first Preclearance airport. Since then, the program has been expanded to a total of 15 airports in six countries. More than 600 CBP officers are stationed in Ireland, Canada, the United Arab Emirates, Bermuda, the Bahamas and Aruba. U.S. Customs and Border Protection thus handles over 22 million border controls outside the United States each year.

If you use the Preclearance check, you will of course still ask yourself what the procedure is like at the US airport.

Due to the high security standards, the separate waiting area, which is used exclusively by Preclearance passengers, is comparable to US territory. Arrival in the US is therefore as uncomplicated as a domestic flight.

Preclearance passengers

• are not subject to CBP border controls
• may go directly to the baggage drop-off points and / or
• are allowed to leave the airport directly.

Source:
https://www.cbp.gov/border-security/ports-entry/operations/preclearance