http://www.slate.com/articles/news_and_politics/crime/2015/06/new_orleans_how_hurricane_katrina_helped_reduce_the_population_of_the_orleans.html

One of the great scandals of the American criminal justice system is that on any given day, there are about half a million people locked up in jail who have not been convicted of any crime. They’re behind bars because they’ve been arrested and are awaiting hearings or trial dates. Some of them are there because they’ve been deemed dangerous, or because a court determined that they could not be counted on to show up for their next appearance. But in many cases, they are in jail because only they couldn’t afford to pay the bail set for them by a judge.