Originally Posted by
hockeyguy
I'm looking at the CBP declaration right now, and as I thought, the only trip details you fill in are a) countries visited; and b) flight #.
Unless Immigration writes the trip details in the "For Official Use Only" section at the bottom (I've never looked to see what they write there), the customs official wouldn't know anything besides where you've traveled. I'm sure they could pull it up on their computers for questioning, but IME, the CBP agents never type anything into a computer when I hand them the form -- they just take the form from me, give it once-over (sometimes not even that), and then wave me on. I doubt they know anything about my trip besides where I've been when/if they decide to do further questioning.
Well, they nearly always ask me the length of my stay so I assumed they recorded that information somewhere maybe with the declaration form, maybe not, you could be correct.
They could never know exactly for everyone as plenty of people leave the country with no airline record: military, driving, some boats, etc. Sometimes these people will fly back in through customs even though they did not leave a pax manifest flight, so obviously they can't know for everyone.
Ciao,
FH