Decay in Southern Gothic
Lots of stuff is falling apart in Southern Gothic literature: people are falling apart; houses are falling apart; towns are falling apart; morals are falling apart. This is decay and decomposition city, folks.
Decay's such a big theme in Southern Gothic literature because the South was, after all, on the losing side in the Civil War, and this loss permanently changed the Southern way of life. The end of slavery meant the end of the Southern economy, and that led to a sense that the whole culture and society of the South was falling apart.
So the theme of decay and decomposition is prominent partly because Southern Gothic writers were writing at a time when the South was in decline. But Southern Gothic writers also often reflect on how the South's history of slavery and racial oppression itself led to moral and social corruption: the South brought these problems on itself, they seem to say.
Shmoops:
The house that Ms. Emily lives in in William Faulkner's short story "A Rose for Emily" is already falling apart at the beginning of the story. Check out how the narrator describes this decay here (Quote #1).
Blanche, the heroine of Tennessee Williams' A Streetcar Named Desire, is an alcoholic who is falling apart. In these quotations from the play, we see how she's unraveled by alcohol.