And yet Europe has the Schengen area, where people are allowed to travel without requiring documentation, from Portugal to the far north of Sweden, despite some pretty different cultures. Where else in the world is there anything like Schengen?

There's this massive myth that Europe is all one culture, and it's not (you may even have heard about a sizable war in the past century that was predicated on cultural differences).

All countries have a variety of cultures. The U.S. has Alabama, New York City, Utah, Hawaii, the Bay Area, etc. You can always find a way to split people and set them against each other. There's the West; Europe and other Western nations; the UK and other countries; England, Scotland and Wales; London and the rest of England; different parts of London; different religions and ethnicities, the punks and the mods, etc, ad infinitum.

But I don't see any purpose to that. You also can unite people and get great things done together, as 13 very different colonies did in 1789. Why choose fighting with that alternative?

> you may even have heard about a sizable war in the past century that was predicated on cultural differences

I disagree. The cause of the war was one country trying to conquer the other ones. And each side was composed of countries of different cultures and languages. Germany, Japan and Italy; and the U.S., Russia, France, China, etc. on the other side.

And in fact, the EU was created to prevent another war; togetherness has succeeded: The idea of war inside the EU is now absurd.