Max Eden (a colleague of mine at the American Enterprise Institute) and Jay P. Greene write:

In a recent report for the Education Freedom Institute, we set out to answer the question: How many books reported as banned have actually been banned, according to the common understanding of that word? We examined PEN’s April 2022 report, “Banned in the USA,” which found 2,532 instances of books being banned. Our method was simple. Most school library card catalogs are publicly accessible online. So we checked each instance of a book being banned from a library or, in PEN’s phrase, “banned pending investigation,” to see if the book was still listed as available. As it turns out, almost three quarters of the books that PEN listed as banned were still available in school libraries in the same districts from which PEN claimed they had been banned.