The southern part is easy: we're in the American South, shortly after integration. But Gothic? Does that mean, like, castles? Gargoyles? Goth kids?
Well, kind of. Gothic lit dates way back to the mid-1700s, with European Romantics getting their spook on with castles, tyrants, and captivity. Around the 1930s, Southern writers like William Faulkner and our own Flannery O'Connor started playing with similar elements—but instead of castles, they used decaying mansions; instead of tyrants, they used oppressive families; and instead of captivity, they used, well, captivity—of the slavery kind.
The Gothic is a little suppressed in this story. After all, it takes place on a bus heading to the Y. But we do get hints of horror through the use of adjectives and sensory details found in the opening scene: "The sky was a dying violet and the houses stood out darkly against it, bulbous liver-colored monstrosities […]" (5).
And later, during the climax, the violence comes; Carver's mother "explodes like a piece of machinery" and hits Julian's mother with a "black fist" and "the red pocketbook" (102). Organs, death, and smackdowns? Not exactly a light and airy atmosphere.
Not to mention the "decayed mansion."