With Detroit falling deeper into debt and the local government helpless to respond, governor Rick Snyder declared a financial emergency in the city on Friday. The next step is to appoint an emergency manager who will be tasked with turning Motown around.   Nobody says it will be easy, but it's been done before. In the 80s and 90s, industrial giant Pittsburgh began hemorrhaging factory jobs. Smoke stacks stopped puffing and the amount of vacant properties skyrocketed. Don Carter, the director of urban design and regional engagement at the Remaking Cities Institute of Carnegie Mellon University  explains how the city bounced back from bleak job losses and economic depression.   More recently, New Orleans took both a physical and economic hit when Hurricane Katrina made landfall in 2005. Since then, residents have been working to rebuild mainly the poorer parts of town that were hit hardest by the storm.  Nick Spitzer, producer and host of American Routes, describes what that process has looked like.