> And once you have probable cause, you run into the problem 8 USC 1304(e) creates: someone who doesn’t have documentation proving their legal immigration status falls into one of two categories, they’re either a citizen, or they’re an immigrant violating that section.
So hopefully if you are tourist from abroad, CBP will give you stamp into your passport, otherwise you have entered "illegally". They are not always stamping passports.
CBP is doing it electronically for quite some time, as they can see your date of entry in the system and they are not controlling your date of leave against passport when you are leaving USA (you won't even meet CBP at that stage), but it is all checked electronically.
Last time I got stamped. But it seems like an exception than a rule.
A lot of countries don’t stamp passports — if you can guarantee the entry is immediately recorded in your central database, and you can reliably look up the latest entry for a given passport, a stamp doesn’t really gain much.
So hopefully if you are tourist from abroad, CBP will give you stamp into your passport, otherwise you have entered "illegally". They are not always stamping passports.