Harper Lee's To Kill a Mockingbird is set in the American South during the 1930s. This setting connects to the novel's overarching themes of prejudice and racism. The characters in the story live in Maycomb, Alabama, a town populated mostly by racist people.

The 1930s mark a period in American history known as the Jim Crow Era. This period occurred after the Civil War and abolishment of slavery; however, Black people were still subject to racist treatment and laws. The Jim Crow laws were designed to segregate Black people. Black people were not truly free. They were forced to use separate and unequal facilities and were not allowed to vote, pursue education, or apply to many jobs. The time and place in which the novel is set thus play a significant role in communicating the theme of racism.

Tom Robinson is a Black man who is accused of raping a white woman. The novel centers around Atticus Finch, a white attorney who defends Tom, and his two children. Atticus knows he does not stand a chance of winning the case, but he accepts the impossible task anyway because he knows it is the right thing to do.

Atticus and his children receive a great deal of backlash from the mostly racist community of Maycomb. The town's white population strongly resents Atticus's choice to defend a Black man. Scout gets into a fight at school with Cecil Jacobs, who voices his distaste for Atticus's choice to defend Tom. Even Atticus's own family disapproves of his defense of Tom. His sister, Alexandra, feels that Atticus is disgracing their family. Francis explains,

Grandma says it's bad enough he lets you all run wild, but now he's turned out a nigger-lover we'll never be able to walk the streets of Maycomb again. He's ruinin' the family, that's what he's doin'.

Atticus and his children endure nasty looks and snide remarks from the people of Maycomb. In chapter 15, Atticus is guarding Tom, who has just been transferred to a jail in Maycomb. An angry mob of Maycomb residents arrives and threatens Atticus and his children. Scout appeals to the familiar faces in the crowd and is able to successfully convince the people to go back to their homes and leave her father alone.

The woman who accuses Tom of rape is Mayella Ewell. She and her family are strongly disliked by the people of Maycomb. Despite their intense hatred for the Ewell family, most of the citizens of Maycomb side with the Ewells simply because they are white. Tom is a kind, hardworking man who is innocent of the accusations against him, but he is convicted anyway because of the racist culture of Maycomb. The people of Maycomb are convinced of Tom's guilt based solely on the color of his skin. Tom is ultimately shot and killed by prison guards while trying to escape from jail after being imprisoned for a crime he did not commit.

Through the novel's setting and characters, Lee calls attention to the horrendous, racist treatment of Black people in the American South during the 1930s.