You cannot use Europe as an example, because, it might surprise you, but European cultures are vastly different from American culture. A lot of the marginalized groups in Europe, have no problem integrating in the US.

And to put the blame of lack of integration purely on the immigrant group is very disingenuous when you have all these far-right political parties openly showing their colours and saying matter of fact that they do not want any foreigners, including legal ones, including educated ones.

And finally, what's the link between integration and crime? I don't see the connection. If anything, the people who are least integrated are the ones who are the most law abiding. The lead a pious life according to their faith. They aren't the ones going around dealing drugs in night clubs. Those drug dealers are much more integrated in the host culture. After all drug consumption is very European.