> The "homogeneous = less crime" argument is a bit xenophobic/racist at best, and not quite true.

Why the ad hominem? It stifles conversation. I think it is entirely legitimate to make the claim that ethnic, and actually more so religious/worldview heterogeneity can cause conflict. Heterogeneity is inversely correlated with trust because trust is formed through understanding and appropriate agreement and these differences often mean misunderstanding and disagreement. You can talk about dialoging as a way to reduce conflict, but even when understanding exists, when one norm must prevail and two groups are in conflict, this will leads to problems. The more fundamental the conflict, the worse it gets.

Look at Yugoslavia. Are Croats, Serbs, and Bosnians "racially" different? No. Language? Not really. So the source of conflict is religious.

The political conflict in the US today is mostly religious in nature, where "religious" is broadly understood.

I don't think France is very heterogeneous. I'd guess it's 80-85% "white" (mostly French, some Italian + other Europeans), remainder mostly North African immigrants, half of whom live in Ile-de-France (Paris metro area). Anywhere outside of a couple cities in France is suuuuuuper homogeneous.

> France is quite heterogenous.

Paris, yes. France, no.

France as a whole is very homogenous.

Immigrant populations in both France and the United States are in the mid-teens, percentage-wise. [1]

Japan's immigrant population stands at 2.0%, and Guatamala's is 0.5%.

I'm aware that there are other measures of diversity, but many of the comments here were mentioning the United States's border with Mexico specifically as a reason for its high murder rate, which doesn't seem to hold up once you dig into the numbers.

https://en.wikipedia.org/wiki/List_of_sovereign_states_and_d...

I think the other measures of diversity are the ones that are important. For instance, an influx of Canadian immigrants to the U.S. would, I expect, cause no problems at all because Canada is by and large very culturally similar to the U.S.

The border is important in my thinking mainly because corruption and organized crime are endemic to Mexico, though immigration of people from a significantly different ethnicity+culture is also important in the U.S. picture.