sarge
Penultimate Amazing
I'm pretty sure that if America suddenly vanished and took all of its pop culture with it, Halloween as we know it would definitely die out. America created it okay America didn't create it but America created it, and American pop culture sustains it. Without America, there wouldn't be the Halloween that we see today. You might see it in some form, but in no way would it be sustained the way it is today. I am absolutely convinced of that.
I agree that Halloween as it is currently celebrated world-wide is a uniquely American export. As currently celebrated, it exists as a direct result of the spread of American pop culture, and owes very little to it's roots in paganism.
However, if (for some strange reason) America suddenly stopped doing Halloween, Halloween would not only continue to exist in places where it currently is celebrated in American fashion, it would continue to spread, although the rate of new communities adopting it would almost certainly slow down. FMO's point about other American cultural exports (Jazz, etc) is valid. People that now celebrate Halloween may have adopted it from the US, but they continue because it is fun.