The formation of ghettos, segregation of society either through self-selection or through the willful exclusion of immigrants by the dominant population, will lead to pockets of reinforcement. If you want people to assimilate into our society, we need to accept them with open arms.

I've been to LatAm and you get grouping in certain neighbourhoods. People from certain countries live close to others from that country too --even if just from other LatAM countries, or from Asia, so I don't think it has to do with exclusion.