The recent spike in book challenges has put school libraries at the center of heated political debates. I investigate the relationship between local politics and school library collections using data on books with controversial content in 6,631 public school libraries. Libraries in conservative areas have fewer titles with LGBTQ+, race/racism, or abortion content and more Christian fiction and discontinued Dr. Seuss titles. This is true even though most libraries have at least some controversial content. I also find that state laws that restrict curricular content are negatively related to some kinds of controversial books. Finally, I present descriptive short-term evidence that book challenges in the 2021-22 school year have had "chilling effects" on the acquisition of new LGBTQ+ titles.