Scout's narrative relates how she and her elder brother Jem learn about fighting prejudice and upholding human dignity through the example of their father. Atticus Finch has taken on the legal defense of a black man who has been falsely charged with raping a white woman.
In To Kill A Mockingbird, the most obvious example of racism is during the Tom Robinson trial. Atticus Finch does a superb job of proving Tom's innocence. He points out that Mayella Ewell was assaulted by someone who is left handed. Since Tom Robinson has a crippled left hand and arm, he could not have beaten Mayella. Although Atticus does a good job of proving this fact, Tom Robinson is found guilty of assaulting Mayella. Of course, the jury is made up of white, racist men. These men ruin Tom's life by finding him guilty.
Racism is at the the heart of Maycomb during this time. Another example of racism occurred when Calpurnia carried Jem and Scout to her church. There were black people who felt the white children should not be there. Racism existed on both sides through both blacks and whites.
During the trial, the blacks had to sit up in the balcony. Blacks and whites were not permitted to sit together. Blacks and whites could not associate with whites. Truly, racism existed in Maycomb.