I don't see that as necessary, given that most of the US remained under continuous democratic governance. The rest... got there eventually.

Even if you do count from the end of the civil war, I would not consider my central thesis destroyed by the small and frankly uniquely weird country of Switzerland. Switzerland is a country that has done very well for its people, but the lessons which have kept it stable and safe over the past two centuries (have a lot of mountains, and don't be worth invading) are not ones which extrapolate out.

And let's be honest -- Switzerland was not functionally independent in WWII. It wasn't necessary to invade, because they did whatever the Third Reich wanted with their stolen gold and borders. This is not the stability I am looking for.