I dunno, I still don't think that you can claim with a straight face that the difference in cultures across the USA is similar (or imo, anywhere close) to that of the same land area in Europe. We're talking a landmass that has been populated, fought over and written about for literally
thousands of years. Each country has its own independent history and culture that has been built up over centuries. Did the Mongols bother Great Britain that much? The Ukrainians are descendants of them. Large sections of Europe spent a long time under communist rule and the effects are still very visible. The ancient Greeks
invented western civilisation.
That's to say nothing of the dramatic differences in weather and climate.
If you go to certain areas of the US, you'll find entire neighborhoods where English isn't even the primary language that's spoken.
That's almost like Europe!
EDIT: Okay I reread through the thread and nobody is really making a point about Europe not being diverse. I'll still remain skeptical that NA countries are that different compared to other continents, though.