Yes... a wall. Hadrian did it. The US can do it too.
This can be George W's wall. (every empire should have a wall, right?) We'll build this one from Vancouver all the way to Nova Scotia.
That'll keep those pesky Canadians them saying anything about the US that we in the US don't like, Hmmmmmm?'
"By, Thunder, by Jeez... what do you know about (pronounce aboot) that... those 'damn' American's built a bloody wall... they can't even take a little joke.... eh?"