Who is the narrator of The Underground Railroad?
The narrator is a third-person narrator who knows Cora's thoughts and history. Though Cora herself isn't telling the story, the narrator is as aware of her as if she herself was narrating. The narrator is a limited narrator. This means that they know everything about the person who they're focusing on for that chapter but not about every person that comes into contact with the focus of the chapter. For example, the narrator doesn't share Lovey's thoughts and feelings when she's interacting with Cora. Only Cora's thoughts are explained to the reader.
When the narrative focuses on another character—like Mabel—the narrator is aware of what that person is thinking and feeling as well. In "Mabel," the second-to-last chapter, the narrator opens with an explanation that the first and last things Mabel gave to Cora were apologies. They also explain that Cora heard neither of them. This shows that the narrator isn't a third-party version of Cora herself but rather an objective outsider who only shares internal information about the central character in a chapter.
While most of the book is focused on Cora, the narrator never changes, even when a chapter focuses on someone else. The Underground Railroad has the same narrator for the entire book.
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