The other aspect is that the jobs left the cities. The two factors here were: 1) corrupt city machine politics and high taxes and fees, union problems, etc. 2) William Whyte's discovery that companies moved headquarters out closer to CEOs' estates so the CEO would have a shorter commute.
60 years of deliberate policy drove middle class people out of the cities. The forced busing is pretty emblematic of what happened.
http://www.amazon.com/Slaughter-Cities-Renewal-Ethnic-Cleans...
The other aspect is that the jobs left the cities. The two factors here were: 1) corrupt city machine politics and high taxes and fees, union problems, etc. 2) William Whyte's discovery that companies moved headquarters out closer to CEOs' estates so the CEO would have a shorter commute.