Nicing Up the City
"[P]eople are rude - in L.A. and many other places - because we live in societies too big for our brains. In a small society in which everyone knows each other, you can't act out the way you can around strangers. If, however, you're around people you'll never see again, you can get away with all sorts of nasty behavior.
We can't shrink Los Angeles to a more polite population size, but we can bring back some of the constraints and benefits of the small tribal societies our brains are adapted for. This actually doesn't take much."
She says that making a place feel neighborly is as easy as being neighborly.