Where is the "Bottom"? How was the neighborhood established and how is the name symbolic?
The "Bottom" is part of the town of Medallion, Ohio, situated in the hills above the town "and spread all the way to the river."
The story of how the Bottom came into being is recounted in the opening chapter of the novel, although the veracity of the story is somewhat dubious as it is introduced in the context of a joke.
A farmer promises freedom and land to a slave if the slave agrees to do some difficult work. The slave completes the tasks and the farmer equivocates, playing on a misuse of language to suggest that the only land he can give the slave is "valley land" up in the hills.
When the slave asks for an explanation as to how valley land could be situated up in the hills, the farmer replies with a roundabout and creative lie.
"'High up from us,' said the master, 'but when God looks down, it's the bottom. That's why we call it so. It's the bottom of heaven—the best land there is.'"
This is the tale of the Bottom's origin, and it expresses the full and symbolic meaning of the term. The Bottom is a social status that we can associate with the physical meagerness of the land and its value as farm land. The name of the town, then, is a statement on the marginal status of the people who live there.
With these various meanings to the name (the bottom of heaven, the location in the hills and the social meaning), the name of the town becomes endowed with irony. This irony is reinforced when, late in the novel, the wealthy residents of Medallion take over the Bottom, replacing the poorest residents of the town with the "top" residents in terms of privilege.
Thus the privileged view from the hills enjoyed by the people of the Bottom was not entirely ironic, though it is ultimately taken from them by the same group that swindled them with it in the first place.