Harrisburg, PA, recently filed for bankruptcy, raising fears that other cities and towns may follow suit. Pennsylvania's capital provides an example of the structural problems, political gridlock, and unfortunate events that, over time, can push a city into an extraordinary crisis.

Even though many cities and counties are under financial pressure, bankruptcies among the more than 50,000 governments that issue municipal debt remain extremely rare. Even the Great Recession has not sparked a dramatic increase in bankruptcies, according to this infographic.