Yeah, I would think the overflow would be to places like Yonkers, Newark, etc. The "poor and dangerous" crowd tend not to stray too far from home. Much of the problem in Philly is not that there's been overflow from other places but that there hasn't been *enough* overflow. Hence, there's been a net population decrease and, with that, disinvestment which has led to poor schools, bad neighborhoods, fewer job opportunities, and all the other elements that lead to violence and crime.