Flights from central america to europe often have connecting flights in the US - and, unlike Canada and most of the rest of the world, the US requires people to

Flights from central america to europe often have connecting flights in the US - and, unlike Canada and most of the rest of the world, the US requires people to pass through US Customs & Immigration to change airplanes. In the rest of the world - you simply stay in the secure international area of the airport, and never have to deal with customs & immigration until you land in your destination.