I've always been a little concerned with this, because large swaths of most cities in America have a condemnation problem. Slum and light exists almost everywhere, not just large metro areas.
Take Sheffield, AL for example. I'm not sure how many of you have been through the area, but there is large sections of the city that can't be sustained. There are some beautiful sections too, and the downtown is undergoing some amazing renovations. There's a lot of neighborhoods with beautiful views of the river, etc.... But there are areas of town that I don't see making a comeback. What do you do with those? In 10-15 years most of those houses will be uninhabitable (if they aren't already). Half are already abandoned. It's a major problem and it exists in almost every corner of America. Not sure the solution, but it's going to become a massive problem if we don't come up with solutions soon.