Its hard to say whether circumstances caused the hatred or whether the hatred was already there and waiting to emerge.
I can understand why people have this backlash, in Europe in particular. You have these ethnic/cultural/historical groups composing the nations, and they've been that way for an incredibly long time. They never really worried about mass immigration posing any problems until it happened and they had large unassimilated populations. Its alarming to see the long established order of things so dramatically affected.
As an American, we haven't really had that problem. We've been one wave of immigrants after another. Every few decades someone feels inadequate and picks on the others. From the Irish, to the Germans, to the Mexicans. Its a passing thing though, and it lacks popular support.
I think Europe is coming up to a crossroads. The political pendulum usually swings pretty regularly, and the swing to the left might be reversing itself. Lets hope the pendulum doesn't go too far.
I always saw it like this: America has been largely insulated from the wider world. You have such low population density and such a large country that immigrants were able to settle reasonably comfortably after each wave (after the initial adjustment period). Most importantly, you were an ocean away from everyone else. The long-standing conflicts and struggles never reached you because you were half the world away. But in Europe/Asia/the Middle East there's
no getting away. We're all here, packed into the same spaces, rubbing against each other full stop. Ethnic groups galore who all hate one another with long-burning passion. America is only just now beginning to realize it can't truly escape. The USA's repeated adventures in the Middle East these last few decades are a sign of that - you're being dragged back into the ongoing mayhem whether you like it or not. And the attack on New York popped America's bubble of isolated safety and served as a rude awakening that as the world gets smaller you're back in the midst of it all.
I've read about the problems in communities along the American border with Mexico, and it's interesting how the issues and concerns there match much of Europe. But for the USA it's just that one border. Europe on the other hand is nothing
but borders. What is regional for America is largely the case everwhere back in "the old world".
