Also the white flight to the county was remarkably debating to the city. The grazing of communities (mill creek for example) for highways that take you around the city, was truly the nail in the coffin. 

 It's all connect, people are going to leave when all the opportunities leave, then the desperate city starts raising taxes on their population that can't afford to leave 

 If you think about it, all the rust belt cities when thru their own mini Atlas Shrugged Scenarios

All the Productive John Galts Vanished