(Tongue firmly in cheek, he said ....)
Yeah, I've mused about how useful a border wall might be between Canada and the USA. For example, in the winter where I live one of the common repeating weather phenomena is a "Colorado Low" that forms in the US Southwest and travels north-north-east across the prairies and then across the Great Lakes, picking up water all along the way. Finally it gets far enough north (usually starting about Minnesota) that it starts dumping all that moisture as snow, and too often a LOT! How high would the wall at the border need to be to stop that?