Driving back and forth to Minnesota takes me across the US-Canadian border on a regular basis. There is a rhythm to such crossings: one rhythm on the Peace Bridge when we fly to Toronto and drive south to Harrisburg; another rhythm on route 59 headed south or north.
Usually the American border guard asks: "Where do you live? Where are you going? Purpose? Citizenship?" Occasionally (as last week), one asks: "Where were you born?" I was born in Zambia, which leads to further questions. The primary concern is always to make sure that someone entering the United States is legitimate.
Driving home I pull up to the Canadian border. The difference between border crossings is striking. My American passport takes me south; my Canadian passport takes me north. But the Canadian guard is normally a Customs Officer, who asks only about purchases. "Where do you live? Where have you been? What did you buy?" If the concern going south is security, the concern going north is finance.
Of course, in both directions the guards have a pretty good idea of what is happening by looking at my licence plate, entering the licence number (perhaps this is done more at the American than the Canadian border), and knowing who crosses here. I know a number of the guards by now; and they know me and many other people.
They know that my Manitoba licence means that I'm coming home (or visiting, as the case may be). But I notice that the American guard always swipes my passport through some sort of electronic screening device, and the Canadian guard may or may not look at my passport (which is sitting plain sight beside me). If the guard doesn't know me, he's more likely to ask to see my identification; often as not he knows me, and may ask a question about Providence to show that he understands exactly where I fit.
I don't know what the experience feels like to people who carry passports from other countries, in Europe or Asia or Africa, when they come to the US or Canada. But for me, it's usually a brief stop and some conversation with people I've gotten to know. I don't envy them their job: there are enough people who try to exploit the good relationship between Canada and the US, and cross under false pretences. But the bigger difference is that the border marks a real boundary between two countries. Northern Minnesota and southern Manitoba are so close, and we share a great deal; but we are really different.
Some day I'll think more about the differences.