Concentrated Poverty is the new Urban Panic.

[MrPots]

I think poor people have always "clustered" in certain ares. We call them "the wrong side of the tracks".

I suspect those clusters are simply becoming larger and more noticable what with stagnant wages and the ever widening gap. I also suspect our major cities will eventually sport our own favelas soon enough (well away from the sight of the wealthy elite...).