It's about who the US owes money to.
From the article:
Amount of U.S. debt: $134.6 billion
Share of total foreign debt: 3.1%
They say that a friend in need is a friend indeed, and our neighbor to the north has proven to be a kind and generous creditor in our time of financial need. Canada holds about 3.1% of our foreign debt, or $134.6 billion. If friend were to become enemy and Canada were looking to annex some U.S. land to cover the debt though, the country would have an easy time of it. The combined GDP of Maine ($51.3 billion), New Hampshire ($59.4 billion) and Vermont ($25.4 billion) comes close to Canada's debt holdings at $136.1 billion.
Residents of the three states in our extreme northeast corner should start practicing their French: They might become Québécois one of these days.
So Matthew, when do you give Alfred the adoption papers for those 3? Maine would likely go quietly. But New Hampshire and Vermont would throw one HECK of a tantrum.