Scotland residents ages 16 and up, but not Scots living elsewhere in the United Kingdom, including those serving in the military, will vote Thursday on whether Scotland should remain in the United Kingdom of Great Britain and Northern Ireland. “Should Scotland become an independent country?” is the question on the ballot.

From an American perspective, this seems like a lunatic idea. But last weekend, for the first time, a poll showed “yes” (for independence) outpolling “no.” The “no” side seems to have regained some momentum, but there’s still a chance Scotland will secede from the UK (which may have to be renamed). How has this come to pass?