From the ALA website:
A Clockwork Orange, Anthony Burgess
In 1973 a book seller in Orem, Utah, was arrested to selling the novel. Charges were later dropped, but the book seller as forced to close the store and relocate to another city. Removed from Aurora, Colo. high school (1976) due to "objectionable" language and from high school classrooms in Westport, Mass. (1977) because of "objectionable" language. Removed from two Anniston, Ala. High school libraries (1982), but later reinstated on a restricted basis. Source: 2004 Banned Books Resource Guide, ed. Robert P. Doyle.
Like most banned books, it's not a general ban nation wide; challenges are generally local.
I have never read this. Is it a difficult book to read word-wise?. Heard so much about it and don't really know anything about it. I only saw parts of the movie, if that makes any difference.