I agree that the coordinated (particularly at a state level) restrictions[1] on books sits largely with the political Right in the US.
However, from around 2010, there has been increasingly illiberal movement from the political Left in the US, which plays out at a more local level. My "vibe" is that it's not to the degree that it is on the Right, but bigger than the numbers suggest because librarians are more likely to stock e.g. It's Perfectly Normal at a middle school than something offensive to the left.
1: I'm up for suggestions for a better term; there is a scale here between putting absurd restrictions on school librarians and banning books outright. Fortunately the latter is still relatively rare in the US, despite the mistitling on the Wikipedia page you linked.
However, from around 2010, there has been increasingly illiberal movement from the political Left in the US, which plays out at a more local level. My "vibe" is that it's not to the degree that it is on the Right, but bigger than the numbers suggest because librarians are more likely to stock e.g. It's Perfectly Normal at a middle school than something offensive to the left.
1: I'm up for suggestions for a better term; there is a scale here between putting absurd restrictions on school librarians and banning books outright. Fortunately the latter is still relatively rare in the US, despite the mistitling on the Wikipedia page you linked.