Almost exactly what I was going to say.I'm not entirely certain what you are asking here, there was and is a non-Spanish monarchy on the North American contienent. We call it Canada, if having the crown held by the British Monarch does not match your peramiters, there could easily be a POD where in order to assert independence while plactating the traditionalists the Canadian Parliament selects a different member of the House of Windsor to assume the throne.
Have a nice day.
-MRegent
Long live Her Majesty, Elizabeth II of Canada!!
(That's serious, not sarcasm, actually. I think we're incredibly lucky in our Monarch, even if we don't see her in person very often.)