The "lack of diversity" in Scandinavia comes up now and then even on HN, but:
In 2010, there were 1.33 million foreign-born residents in Sweden, corresponding
to 14.3% of the total population. Of these, 859 000 (9.2%) were born outside
the EU and 477 000 (5.1%) were born in another EU Member State.
This does not include second or third generation immigrants, nor minorities with a longer presence.
The number of immigrants in Norway is approximately 550,000.
The total "immigrant population", which includes Norwegian-born children
to immigrant parents, is 655,170, corresponding to 13.1 percent of the
total population (2011).
In the US our foreign born population is roughly similar about 13% foreign born in 2009. However the percent of foreign born people in the US has historically been very high.
Wikipedia points immigration to Norway has risen very recently because of it's membership in the European Economic Area. It is entirely possible that united states has issues caused by continued high levels of immigration that Scandinavia has not had time to experience.
Since our foreign born populations are similar, adjusting for that shows that when native born Scandinavians and Americans are considered, Scandinavia is much more ethnically/racially homogenous than the United States.
Furthermore Scandinavia doesn't have a recent history of institutionalized oppression of a very sizable racial minority. There is still a generation of people alive here who actually lived under forced segregation, and more generations who were raised by them.
I'm sure if America was composed only of people who's ancestors came here voluntarily, and who weren't kept as second class citizens for decades, we wouldn't have many of the problems we do.
http://en.wikipedia.org/wiki/Demographics_of_Sweden
http://en.wikipedia.org/wiki/Immigration_to_Norway#Demograph...