What are some significant moments throughout Harper Lee's novel To Kill a Mockingbird where racism is depicted?

There are several significant scenes throughout the novel To Kill a Mockingbird that portray racism. At the beginning of Chapter 11, Mrs. Dubose, Maycomb's most notorious racist, makes several derogatory comments toward Jem and Scout as they walk past her house. She says, "Your father's no better than the niggers and trash he works for!" (Lee 135). Her racist comment upsets Jem so much that he loses his temper and ruins her camellia bushes on his way home from the store.

Another scene in the novel that depicts Maycomb's ugly racism takes place in Chapter 25, following Tom Robinson's death. Scout comments on Maycomb's reaction by saying,

"To Maycomb, Tom's death was typical. Typical of a nigger to cut and run. Typical of a nigger's mentality to have no plan, no thought for the future, just run blind first chance he saw. Funny thing, Atticus Finch might've got him off scot free, but wait---? Hell no. You know how they are. Easy come, easy go. Just shows you, that Robinson boy was legally married, they say he kept himself clean, went to church and all that, but when it comes down to the line the veneer's mighty thin. Nigger always comes out in 'em" (Lee 322).

Tom's unfortunate death only strengthens the racist citizens' views toward African Americans. They believe African Americans are simple-minded and are not surprised to hear that Tom died escaping from prison.

In Chapter 26, Scout's teacher, Miss Gates, criticizes Hitler for his inhumane treatment of the Jews and tells her class that there is no prejudice in America. Scout notices Miss Gates' hypocrisy and tells Jem that she overheard Miss Gates say, "it's time somebody taught 'em a lesson, they were gettin' way above themselves, an' the next thing they think they can do is marry us," while she was leaving the courthouse (Lee 331). Miss Gates' racist comment depicts the deeply ingrained prejudice in Maycomb.