Accidentally returning that copy of Fifty Shades of Grey to your local library a few days (or months) late won't land you in jail, but, depending on where you live, you may be charged a late fee. But where does the money go after you pay the fine?

The American Library Association estimates that there are 119,487 libraries in the United States, a number that includes public, academic, and school libraries. Rules vary from system to system, as do privileges, fines, and practices. We asked the New York Public Library via Twitter how they use money earned from fines, and they responded that "It goes to the library's general funds and is used for the purchase of more materials."

According to the New York Daily News, the Brooklyn Public Library made $1.6 million in fines in 2013, which reportedly went toward "maintaining book and material collections" for a system that needed $300 million in repairs for its 60 branches. Some libraries, like the Northborough Free Library in Northborough, Massachusetts, don't keep the money they collect. Northborough says its trustees didn't want patrons to have a "punitive image" of the library, so all the money goes directly to the town's general fund, in accordance with state law.

Some libraries have waived late fees through amnesty programs because of the effect they have on library attendance (looming fees are a deterrent for those who owe them), and because of the extra time and work it takes to track down late items. (Other libraries, meanwhile, have gone as far as to hire collection agencies to track down those much-needed late fees.)

No matter the policy your local library has regarding fines, it's never a bad idea to pay a visit and check out a book (or something else fun). Your support will mean more than any late fee paid in full.