I would personally love to see a Schengen style area with the US. I remember pre 9/11 governments openly talking about such a thing with sketches in textbooks dreaming of such a day.. Sadly 9/11 ruined lots of freedoms for a generation.
That said, with younger generations who grow up not knowing what pre internet society was like, they are going to wonder why hard borders exist. And once they start voting and having a sizeable effect on policy, things could very well move towards a open border.
open border also brings the US problems north.. Guns especially.
I'm not sure an entirely open border is an appropriate response - but certainly something much less stringent than current regulations. Making it easier for Citizens of each country to cross and live / work in either country, if not entirely Shengen-ish, is a worthwhile cause.
Hell, even moving to UK/EU style exterior border control would be hugely helpful. I went to the UK last year and didn't even talk to a border agent. A scan of my passport was all that was required.
The pre- 9/11 standard was much as it is today if flying; for land border crossings by car, the standard was a valid driver's license, passport or other provincial or federal photo identification.
* pre 9/11 much of that ID did not have associated online databases that were internet accessible. today most do.
I don't think there's anything intrinsic about a passport vs a driver's license in terms of making it more/less likely that someone will smuggle guns.
That is more determined by the rate/success of searches conducted by CBSA, and the associated charges/convictions and penalties.
The only issue whether the ID is easy to fake/verifiable.
Now here's the thing, if U.S. authorities have unfettered access to any given Canadian database (s) I can't imagine an issue from their perspective, and similarly so the other way around.
The only thing is....... that's a lot of databases and associated privacy issues.
Do we want your healthcard records available to U.S. Customs?
On driver's licenses, does this mean CBSA needs access to 50 States worth of DMV records? I assume the States would have to agree, and vice versa for 10 provinces and applicable territories.
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I think there's merit to a somewhat less stringent/cumbersome level of border control, but the how we get there would be no small challenge.