The Adventures of Tom Sawyer was published in 1876, and it was almost immediately met with consternation. That same year, it was removed from the children's section of the library in Brooklyn and in Denver. Less than a decade later, it was challenged in Concord, Massachusetts, and this trend continued until as recently as 1994, when it was challenged in West Chester, Pennsylvania. Two countries banned it entirely: the USSR in 1930 and Brazil in 1937.
Various reasons have been provided for banning the novel, and they express the desire to shelter children from it. The reason given most often in our modern world is that the book uses the n-word, which appears in the work almost a dozen times. Some tried to "correct" this issue by publishing a new edition of the novel that replaces the word with the term slave. This edit was met with widescale criticism, even from those who acknowledge that the term is inflammatory and makes the work tricky to teach. Many argue that the edits lessen the impact of racist characters in the novel, and one of Twain's central goals was to present the complexities of racial relationships within his historical context.
There are certainly other reasons why the novel has been challenged over the years. Some adults see Tom Sawyer as a poor representation of acceptable behavior for children. It was been deemed "trash" that is simply not worth reading. On more interpretive levels, some believe that Tom represents communism and a subversive, dangerous personality that might negatively influence youth.
The Adventures of Tom Sawyer is certainly a work that involves complex themes, yet many adults miss the opportunity to explore its irony and historical context because of their initial reaction to its language.