Thought of this when watching the movie Maria Full of Grace last night (good movie):
I don’t recall when I left the US for overseas (in early 1990s) a very rigorous checkpoint system. Seems like this would be another ideal time to catch people who came illegally. Granted, maybe a bit harder since they may not be smuggling. But still, seems likely people who came in and over stayed or what not, or who walked in the country and now have fake papers, could be caught. Are there checkpoints when leaving the country? I just recall getting on the plane with everybody else like we leaving for Iowa. My memory might fail me, as I recall the hassle of coming into Miami from overseas better.
Non-immigrant aliens, when entering the US, are given a form (I-94) to fill out with their date of entry (among other info). They’re supposed to surrender this form when they leave. However, often many airlines have been in collecting these forms, and the US Government’s system of matching them up hasn’t always been completely up to scratch. For obvious reasons they’ve been working very hard at improving this system in recent years. Eva Luna could give you more detailed info, but I’m not sure if she’s reading the boards while she’s on vacation.
The other part of the answer to the question is what do they do about American citizens (or people claiming to be American citizens) who want to go overseas/across a border?
While you don’t have to go through Customs (which is probably a significant part of the hassle you remember from coming in from overseas) they do check your passport at the airport when you check-in and check your luggage. If you do not have a valid passport, you will not be getting on the plane.
Walking to Canada, they are a little more casual, but a Driver’s License (which does not constitute proof of citizenship) was still required when I did that two monthes ago. (Which actually felt like fairly tight security, because I know I’ve crossed at that same border (Niagara Falls) by stating my citizenship and my place of birth before. )
Anecdotally, it is possible to cross the Canadian border as part of a group and not have your identification checked and then run in to problems getting back. The case I am aware of involved a teen age boy who crossed into Canada as part of a “youth choir” on a bus but the American officials checked each one’s birth certificate, etc. and refused to let this kid (Born in Latin America) through. A few phone calls, and he was released the next day.
It seems like the return on investment of detaining such people, when they are about to leave the country under their own power, would be very low. The US government would be buying itself the opportunity to perhaps eventually deport these people.
I actually wonder why the US doesn’t make everyone leaving on an international flight go through Passport Control on their way out, as several other countries do. That way they could collect the I-94s themselves instead of relying on the airlines to do it.
AFAIK, the airlines check passports/visas for country of destination because an airline that allows someone to board without a valid visa can be fined USD10,000.