In the novel "To Kill a Mockingbird," when Miss Maudie's house burns down, how does this symbolize or relate to racism?

Possibly the most significant reference to racism in the incident of Miss Maudie's burning house would be the 'morphodite' snowman.

In Chapter 8, Jem and Scout use snow from Miss Maudie's yard and soil from their own back yard to build a snowman. Jem first builds the snowman by forming the snowman's body and head with soil. When Scout protests that no one has 'ever heard of a nigger snowman' before, Jem tells her to be patient, because the snowman 'won't be black long.' Sure enough, as soon as the earthy snowman is packed with fresh, white snow, it begins to take on the look of a typical snowman. Above all else, the snowman even looks like Mr. Avery, who the children detest. As matters stand, Scout and Jem are extremely proud of their creation.

Later that night, Scout is woken up gently by Atticus: Miss Maudie's house is burning. What is most interesting about this fire is the panoramic view of the scene we get from the children's perspective; all of Maycomb seems to be fighting the fire. Men and cars throng the street where Miss Maudie's house is located. More men are pushing the old Maycomb firetruck to the scene of the fire. Meanwhile, other men are helping to retrieve and to save some of Miss Maudie's furniture from the burning house. Even Atticus is in on the action; he is seen carrying Miss Maudie's most prized possession, her oak rocking chair, out of the house.

In the meantime, Boo Radley covers Scout up with a blanket while she is entranced by the chaotic scene before her. She doesn't realize what Boo has done for her until later. As the fire recedes and the activity dies down, both Jem and Scout are sad that their snowman has also been destroyed.

As far as a symbol for racism, the fire foreshadows the trial by fire that will test the societal integrity of Maycomb in the wake of the Tom Robinson trial. Also, the destruction of the black and white snowman represents the racism that will threaten the peace and solidarity of both the black and white citizens of Maycomb.

We definitely see how racism affects everyone, both black and white, as the trial commences. For example, the children encounter racism from Lula, a member of Calpurnia's congregation, who doesn't want the children to attend the predominantly black church. Meanwhile, Aunt Alexandra thinks that Atticus should dispense with Calpurnia's service, as she thinks that Calpurnia will prove to be a bad influence on the children, particularly Scout. The most egregious case of racist behavior would have to be that displayed by Mr. Ewell.

In the end, just as some of Miss Maudie's most prized possessions were able to be saved from the fire, Maycomb manages to preserve some element of integrity and decency in the wake of the trial. For example, Boo Radley's kind gesture with the blanket foreshadows the part he plays in saving Scout and Jem from Mr. Ewell's attack later in the novel. Another example is Calpurnia's defense of the children when Lula's ugly behavior surfaces.

The message is that, although the fire destroys Miss Maudie's house, it doesn't destroy the resilience of the human spirit. Likewise, racism does not destroy the best elements of Maycomb society despite its polarizing destructiveness.