This article was largely, well, stupid.
Sure, Denver is only 10% black, a whole 2.5% less than the national average. Give me a break! 1 out of 10 people are black, and 1/3 are Hispanic, that seems far more diverse than Scandinavia.
Another city, Austin, 35% Hispanic and 5.5% asian. Very diverse if you ask me. Again, 8% black does not mean the black community has no presence. There are still a lot relative to some places in this country.
As for Minneapolis, Wikipedia says the city itself is 17% black.
Essentially, this article is total BS