It's just different. The lower 48 is roughly twice the size of the Schengen area, without any border control anywhere.
Throw in Mexico, Canada and Alaska and you are up to 6 times the area, with 3 borders (and the Canada-Alaska border is sort of its own thing).
"It's a big place" doesn't really relate back to border control policy, but the borders of the U.S. and Canada aren't really all that similar to the borders of countries like the Netherlands or Spain.
Yeah. I was thinking more about the physical scope of it and the variety and amount of traffic.
I imagine it would be far less expensive for the U.S. and Canada to just open the border and spend some of the savings on policing any problems from that, but I don't really expect that to happen in the near future.
Throw in Mexico, Canada and Alaska and you are up to 6 times the area, with 3 borders (and the Canada-Alaska border is sort of its own thing).
"It's a big place" doesn't really relate back to border control policy, but the borders of the U.S. and Canada aren't really all that similar to the borders of countries like the Netherlands or Spain.