The Jewish ghettos were formed by completely different people, in a completely different time, for completely different reasons.  This is not a fair comparison, at all.  I suggest you read the old novel "The Rise and Fall of the Third Reich".  This novel clearly explains Hitler's rise, the jewish ghettos, and the reasons for.  There is NO comparison between immigrants not assimilating, and Jewish ghettos and Christians.  Please do not make such comments when it is obvious you lack the contextual knowledge.