What is the history of efforts to censor or ban Huckleberry Finn?

Huckleberry Finn, almost from its publication in 1885, has been the subject of banning and censorship. Just one month after its publication, the public library in Concord, Massachusetts banned the novel, saying it was "trash and only suitable for the slums." Throughout the 20th century, the book has been banned from school libraries and kept out of classrooms because of its depiction of blacks, Huck's penchant for lying, and Twain's use of the vernacular. In the 1950s, the NAACP challenged the book for its use of the word "nigger"; in 1998 a parent in Arizona sued the local school board over the book, saying that it exacerbated racial tensions. Huckleberry Finn was no. 14 on the American Library Association's list of "most banned or challenged" books for the years 2000-2009.

For all the attempts to ban the book, it was nevertheless considered a masterpiece fifty years after its publication, lauded by T.S. Eliot, Ernest Hemingway (who said "all American writing" comes from it), and Ralph Ellison, among others. Critical consensus is that the novel, far from stereotyping blacks, provides a powerful critique of racism.