Regionalism refers to a style of writing in which the narrative of the story is written so as to "concentrate on the landscape, dialect, customs, and folklore specific to a geographic region or locale."
The irony starts quickly in "The Ransom of Red Chief." The landscape is described as being "as flat as a flannel-cake" but the town located on that plain is named "Summit." The story's narrator, Sam, endeavors to make himself sound sophisticated as he tells the story, but the dialect reflects Southern influence and the inadequate preparation for their plan that causes the failure of their plot.
Bill and me figured that Ebenezer would melt down for a ransom of two thousand dollars to a cent. But wait till I tell you.
What Bill and Sam don't know until it's too late is that the citizens of Summit all know "Red Chief" and are only too happy to be free of his mischievous behavior for awhile. Their lives can continue in the same pattern as always, only more peacefully than normal, while the boy is out of the scene.
There don't seem to be much excitement around Summit on account of his disappearance; but maybe they haven't realized yet that he's gone. His folks may think he's spending the night with Aunt Jane or one of the neighbours.
The dialogue of the story supports the atmosphere of the locale as well as the action and interaction between the characters.