https://en.wikipedia.org/wiki/List_of_countries_ranked_by_et...
The second list says - Sweden Ethnic Fractionalization : 0.060000
US EthnicFractionalization: 0.490100
So it says America is 8 times more diverse than Sweden.
Sounds about right. That makes Sweden a lot more homogenous than the US.
The first list is really screwed: it lists Italy and China as among the least diverse - which is rubbish.
That’s because it only includes linguistic diversity- not ethnic diversity. So Sicilians and Milanese are grouped together, as are Han and Tibetans.
Latin America becomes much less diverse, because the many ethnicities speak Spanish, etc.
Look at how undiverse Cuba is!
America has a large number of different cultures, ethnicities and religions, but to get a decent job you need to English.
My link shows that there is a bigger share of immigrants in Sweden (19%) than in US (14%).
I think cultural diversity weighs more here than skin color.
I've not yet fully understood why a large population or area or ethnicity would generally impede things so much, but maybe it's just misattributed and there's sometihng about system of governance or the population's general distrust of government makes it hard to get things done there.
Of course there are some genuine things that scane sub or superlinearly with population size. For example network effects are bigger in bigger populations.