I don't think that's accurate. Europe is almost entirely European, Asia is almost entirely Asian, Africa is almost entirely African. Even Wisconsin at 86.5% white is less white than most European countries. And Milwaukee itself is 40% black and 17.3% Latino.
The countries that come anywhere close to the US on diversity are predominantly the other countries in the Americas.
This has to be sarcasm, right?
If not, this view is very wrong because it views diversity in a manner that's purely and literally skin deep.
Which means there aren't a lot of people of any race who are culturally Japanese in Africa or culturally African American in Europe.
The category "white people in America" has that level of cultural diversity inside of it. It includes millions of first generation immigrants from all of those places. Plus millions of people descended from those cultures who over the past centuries have developed them into something uniquely American, melding them in a thousand cities with the cultures of all the other immigrant populations that have come here since then.
And we can't pretend that no country in Europe has ever sinned. Or any country anywhere for that matter.
Of course Asia is full of Asians; but they represent an incredible diversity of ethnicities. In some areas, they are geographically mixed, in others not.
Moreover, if you can bisect Asians into Japanese and Koreans etc. then you can bisect whites into Irish and German, Latinos into Colombians and Venezuelans, blacks into Jamaicans and Haitians etc. And if you're going to play that game then why aren't the racially segregated areas still internally diverse in the same way? Certainly they are as much as the countries that consist almost entirely of that category of people are.
My original comment was to explain how the statement, "Knowing that the US is probably one of the most segregated countries . . . " is incorrect.