Hurricane Katrina was a stunning example of complete civic breakdown. Beginning on August 29, 2005, the world watched in horror as--despite all the warnings and studies--every system that might have protected New Orleans failed. Levees and canals buckled, pouring more than 100 billion gallons of floodwater into the city. Botched communications crippled rescue operations. Buses that might have evacuated thousands never came. Hospitals lost power,...