An interesting report in the Chronicle of Higher Education (Jan 9, 2011). In the US, anywhere within 100 miles from the international border or the seacoast is considered "border area", and the Border Patrol is allowed to check citizenship / immigration status of any persons there. (In practice, I assume, they don't go after "any person" - since perhaps a quarter of the US population lives within 100 miles from a border or a seacoast - but try to identify suspicious persons based based on their appearance, speech, and behavior). Traditionally, the area along the Mexican border was their main stomping ground; but now sufficient funds and manpower have been allocated for the Border Patrol detachments along the Canadian border as well - including in places like Rochester, NY, which doesn't even have an actual land border with Canada. Not having actual illegal border crossers in the area makes the Border Patrol look for immigration violators wherever they potentially can be found - e.g., aboard Chicago-New York trains that happen to cross Upstate New York, and on the local road. An upshot from this over-abundance of funding is that foreign students and staff members in US universities located within 100 miles from the Canadian border found their papers checked frequently - and they don't mean just one's student ID or a local driver's license, but the full stack of paper establishing one's legal status in the US at the moment: the passport, the I-94, the I-20, and any additional paperwork that may have been added as one's situation changed. The originals, not copies! From the practical point of view, this is of course a hassle and somewhat of a risk. Losing one's passport and associated paperwork while in a foreign country is an expensive proposition: Australia, for example, would charge $326 to replace a lost/stolen passport, while the USCIS will charge another $330 to replace a lost I-94 (a little slip of paper that goes inside one's passport). So no wonder most people would rather keep things like this in a safe deposit box. According to the article, the least pleasant effect of the checks is on people whose current immigration status in the US, while perfectly legal, is not that easy to determine (at least, for an average Border Patrol agent) from the paperwork they possess: namely, those who have applied for an "adjustment of status"(e.g., from an authorized foreign student or foreign worker to permanent residence). Some get detained and locked up for hours or days, even though the totality of the documents that they have in their possession is sufficient to proof their current legal status.