Interesting, I always wondered about US border agency though, to what kind of information they have access.
I remember being asked where I worked and what my position was while being processed at the US border, officer was staring at the monitor meanwhile (to see if I lie or not?).
Do they really know where I work, how much money I make etc..? A bit scary
P.S.
I am Canadian and was visiting my US wife when this happened.