You don't really need the high density part, though. Let's take a small mill town I know as an example. The mill closed in 2000, and left half the town unemploy

You don't really need the high density part, though. Let's take a small mill town I know as an example. The mill closed in 2000, and left half the town unemployed. Many of the people living there are still without full time jobs. They live in houses; how can they do that? They either bought a house years earlier or it's because rent for an entire house is about $340 a month. Multiple people live in the house, so that cost is split. They can live there legally and without resorting to squatting.