The prospect of America expanding north is a reminder of the historical threats of invasion Canada has faced, and efforts toward closer economic integration.

The U.S. is threatening a two-stage tariff plan in which Canada and Mexico could get hit with initial trade penalties within days then face broader penalties this spring. In summary it's: Maybe tariffs now, and maybe more tariffs later.

Having already forced Colombia to accept deportees by threatening a 25% tariff, President Donald Trump is readying the same move against Canada and Mexico as soon as Saturday. But this time, the stakes are higher and many economists surveying the possible damage doubt Trump would be comfortable with what they say would be self-inflicted wounds from the tariffs.