Answered By: Gabe Research & Writing Studio Last Updated: Jan 14, 2016 Views: 22
The American Library Association keeps the most comprehensive list of challenged books and why they are challenged. It is part of an effort to advocate against book banning, so the information they provide does have an agenda associated with it. Their website is here: http://www.ala.org/ala/issuesadvocacy/banned/index.cfm.
Below are links to the biannual guides: