Or just educated in history.

Really, what is the longest period of time a country has existed without a repressive regime coming to power and abusing the institutions and populace?

And without a massive war? The USA has had 151 years of uninterrupted peace.

Just as an example---because the old rivalry was USA vs USSR---Russia has endured two devastating and traumatic world wars, a revolution, a civil war, and Stalin. And they still rivaled US power throughout the cold war.

I think Americans really overstate the effectiveness of their economic and political system, and understate the huge advantage they have geographically.

151 years of uninterrupted peace? I think you're forgetting about some conflicts.

Now, if you're talking just about wars that don't involve enemy attacks on American facilities, then technically World War II still counts. So no, not 151 years.

With that said, I do agree with your final sentence.

I don't know exactly how long, but I'd venture to say it's one of the small extremely homogeneous European countries like Switzerland or Denmark.

It's an interesting question to ponder about in your free time.

With of those you're looking back about as far as 1815 and the Napoleonic wars, if you're counting backwards from today.

Britain (well, England) has managed a good 350-450 years before.