OK, here’s the plan:

We build a wall.
Now that we know without a doubt how things are, we need to be proactive.
So, c’mon Canada – let’s all meet at the border and have a Wall Raising. I bet we could get materials and funding from the US, who would no doubt be happy to help delineate exactly where we begin and they end. After all, border control is a big issue. What if a cow inadvertently meandered across the currently invisible border into Montana?
Think of the advantages*:
– Jim Carey and Celine Dion would be permanently on the other side of the wall.
– There would be loads of jobs created in wall building, wall maintenance, and graffiti removal.
– Graffiti!
– Bush League and other prominent targets safely on other side of the wall, thus reducing possible shrapnel-related injuries.
– No more brain drain (except of those smart enough to get over the wall).
updated suggestions from Vinny:
-easy practice for tennis players
-Meryl Streep can try to bring her children across another wall in another movie
-brick stocks will shoot through the roof
-if we build it high enough, we won’t be able to see their humvee2 vehicles
-can finally develop a semi-charming national accent.
*Suggestions for other advantages are welcome, invited, and will be posted in updates.