PEN America has released “a cumulative data summary” of the nearly 6,000 book bans in public schools that the organization has documented since July 2021, identifying two especially noteworthy phenomena: “copycat bans” and a so-called “Scarlet Letter” effect.

In the report, titled “Spineless Shelves: Two Years of Book Banning,” PEN officials note that many of the books banned in one district are frequently banned in others, often in other states—a trend PEN ties to organized political groups compiling and sharing lists of titles to target. The report cites the work of Sarah J. Maas, the bestselling author known for the Throne of Glass, A Court of Thorns and Roses, and Crescent City fantasy series. In the 2021-2022 school year, Maas’s books were banned 18 times across 10 districts. The following year, that number surged to 158 bans across 36 districts—a 778% increase.

The report also describes a “Scarlet Letter” effect, with authors finding many of their works banned after one of their works is targeted by book banners. The report again points to Maas, noting that in the 2021-2022 school year, eight of her titles were banned, which doubled to 16 titles the following year.

“Book banners have effectively marked a group of authors with a ‘scarlet letter,’ which has intensified the pace and scope of book banning in schools,” said Kasey Meehan, Freedom to Read program director at PEN America. “We have long raised alarm over book bans undermining the freedom to read for students and families, but we are similarly concerned about the effects on authors, and the freedom to write.”

Among the report's other key takeaways: There has been “a sustained focus on banning books written for young adults,” especially when those books are about “difficult topics,” such as violence and racism, or include “historically marginalized identities,” mainly those of people of color and LGBTQ+ individuals; Florida and Texas have continued to lead the country in number of bans, but the crisis has spread to 41 states; and the book banning efforts over the last two years “have been more comprehensive and potentially more permanent.”

PEN America defines a school book ban as “any action taken against a book based on its content and as a result of parent or community challenges, administrative decisions, or in response to direct or threatened action by lawmakers or other governmental officials, that leads to a previously accessible book being either completely removed from availability to students, or where access to a book is restricted or diminished.”

Overall, the report, which pulls together data from PEN America’s July 2021 to June 2023 School Book Ban Indexes, notes that 247 school districts across 41 states have faced book bans over the last two years, affecting “millions” of students. In all, PEN America has tracked 5,894 instances of book bans.