Answer: Detroit.
Here are excerpts from the USA Today article, "Detroit: How the Motor City went bust."
Detroit, the once-thriving Midwest metropolis that gave birth to the nation's auto industry, is now the largest city in U.S. history to file for bankruptcy...
• The city's unemployment rate has nearly tripled since 2000 and is more than double the national average.
• The homicide rate is at historically high levels, and the city has been named among America's most dangerous for more than 20 years.
• Detroiters wait an average of 58 minutes for police to respond, compared with the national average of 11 minutes.
• An estimated 40% of the city's street lights didn't work in the first quarter of 2013.
• Roughly 78,000 city structures have been abandoned...
The U.S. Bankruptcy Court filing represents perhaps the biggest body blow yet to a faded city that's now home to barely 700,000 — down from a peak of 1.8 million during the auto industry boom years of the 1950s — and struggles to cope with the abandoned buildings and decaying municipal services.
The filing listed more than 100,000 creditors and more than $1 billion in estimated liabilities, but Orr has said Detroit's total financial responsibilities could be as high as $20 billion...