In December 1978, Cleveland, Ohio became the first in the United States to default on its debts since the Great Depression. The city, soon nicknamed "Mistake by the Lake," owed six banks a total of $15 million. It took 22 months -- and a new mayor, George Voinovich -- for the city to regain financial solvency.   In the next few days, Detroit Mayor Dave Bing will decide whether to appoint an emergency manager for the bankrupt city. Thomas Sugrue, professor of History and Sociology at the University of Pennsylvania, explains what lessons Detroit should learn from the history of Cleveland's default and recovery.