"Both the number and proportion of the poor living in suburbs has increased steadily. In 1970 only 20.5 percent of the nation's poor lived in suburbs. By 2000, that had grown to 35.9 percent. And those trends have continued.
...As the affluent move to upscale enclaves, they bring expensive shopping malls with them, leaving behind older retail districts and abandoned industrial parks. The older housing stock in the troubled suburbs--built in the 1950s and '60s--now requires substantial repairs but many residents can't afford them, and many banks won't make loans anyway--a new kind of 'redlining.' "
Thanks to The Practice of New Urbanism