I didn't want to hijack Yaatri's thread, although my hypothetical questions stem from his experiences.

Let's say you fly to Guam quite a bit. Now, while some US carriers have flights through Honolulu and other places, several flights go through Tokyo as well. If you stay airside the entire time in Tokyo, you would still have to fill out a customs form, etc for your 'stop' in Japan. Does that count as an international flight and bump up your 'watch list' number, even if you never actually entered a foreign country, but only used it for transit?

Second: Say on a European flight from the US, you fly into France on your way to Italy. Again, you are only stopping in France to change planes. Do you declare both France and Italy on your customs form when returning to the states, even if you really didn't do anything in France other than change planes? Does this 'up' your number based on the number of countries you stop in?

I have never been able to figure out what constitutes a trip for an American who lives overseas.

Let's say that I live in Israel and my last visit to the US was April 2006. Since then, I have flown TLV-MXP, TLV-CDG, TLV-FRA and TLV-MAD.

April 2007 comes and I fly back to the States. Am I only supposed to list Israel, or also Italy, France, Germany and Spain?

I would only list the countries involved in that flight to the states. How would immigration know where else you've been in Europe without passport stamps? Once you get 'scanned in' to Europe, I don't see how they could track where else you've been unless the immigration officer has access to your credit card records or other means.

I guess you would have all those stamps in your passport, though, if you are traveling between Israel and those countries and then returning. I guess it also depends on which passport you've used (I'm assuming you have both a US and Israeli).

I don't normally list nations I am in-transit at, unless I actually enter the country. If I fly through ICN but never leave the airport, it doesn't get listed. If I fly through NRT but leave the airport to visit Narita City for a few hours, I then put Japan on my form.

When I am flying back into the USA with an en-route connection, sometimes I will usually put "transit-XXX only" (xxx=airport code) and then a list of countries I have been to. For example if I fly to Spain and transit LHR on my outbound (i.e. SDF-ORD-LHR-BCN) and return via AMS (BCN-AMS-ORD-SDF), I will put "Transit AMS only, Spain" on my declaration. Since it is obvious I am arriving on the AMS flight (or from DXB, NRT, or whereever), etc., that is what I will put since I never entered the country formally. With Europe and Schengen it can be argued you were in The Netherlands before you pass through Schengen exit passport control in AMS if coming in from another Schengen country like Spain. You may have not left the airport, but you took a flight from Spain to The Netherlands, deplaned in The Netherlands (also a schengen nation), and then left the Netherlands via Passport Control at AMS.

When living overseas, I generally include all the countries I have been to since my last entry to the USA. If the CBP officer flips through the passport, he/she would see all the exit/entry stamps.

FWIW - I used to have on-going problems at US customs several years ago, but no longer have any issues. If I get asked anything these days, it is usually how long have I been out of the US. Sometimes I'll ask for a US entry stamp if they don't stamp my passport so that I have a record of entering the US (primarily if I am traveling from a nation that doesn't have an exit stamp or if I have been out of the US more than 6 months).

What do others do when coming in from a transit airport and/or when they reside abroad and return to the US?

Same. If asked I'll say I was in transit and show itinerary. I sometimes make an exception and list the first country I passed through on the way out even if it is a transit, if it otherwise will appear odd to the officer - in order to preempt further questioning.

I live in Japan -- when I've reentered as a non-resident, I've put "none" in the countries visited and also put the amount of goods being declared in the visitors box. Never had any questions on it.

If I were to connect somewhere outside of Japan on my way into the US I'd list it, but if I listed everywhere since the past trip to the US it could become a very long list.

hamburgler