Thanks for all of your replies! Gigneil, I'm pretty sure that in the US, it has always been this way, even before 9-11. You may have noticed this considering that you live in the US, but in a lot of US airports, there are international terminals if they are big enough airports, but some domestic flights still leave from these terminals. In Europe, I have noticed that you go through customs on departure too and then you are in the international area. If you wish to leave or go to another part of the airport, you must reclear customs, even though never left the country. To me, this system seems to be effecient because you can come in from one country, just stay in that terminal, and then get onto a flight to another country without having to spend a lot of time in customs. Most people aren't going to be leaving the terminal anyway if they are there to catch a flight, so it doesn't matter that they'd have to clear customs to leave the terminal. In the US though, like I said, domestic flights sometimes leave from the international terminals, so it would be stupid to put people who are just flying to Florida through customs because they were in the international terminal. By just making everyone go through customs, you can go anywhere in the airport and not have to worry about that. That's just my reasoning though.