Answer:
During the nineteenth century, American identity was undergoing a transformation. During the eighteenth century, much of the academic and artistic life of the nation was reduced to the East Coast and the Thirteen Colonies, and American identity, as something separate from English identity, had not been fully developed yet.
This changed during the nineteenth century. Authors such as Mark Twain and Walt Whitman wrote about what it meant to be an American, and their experience was one that did not resemble that of Europe. They focused on phenomena that was uniquely American, such as expansion and slavery. This allowed them to develop a unique American identity.
Step-by-step explanation: