This dissertation aims to compare two distinct ideas of national identity in Brazil and the United States in the late 19th century. The focus is on the works of Oliveira Lima in Brazil and Jackson Turner in the United States. The idea of national identity is analyzed in terms of the concept of imagined communities proposed by Benedict Anderson, in which members of a society, unknown to each other, feel bound together by common symbols, references and experiences. In the work of Oliveira Lima, the imagined community is constructed by the State - in this case the Monarchy, which came to Brazil with D. João VI in the early 19th century. It is an idea of identity characterized by the fusion of European symbols and institutions with local elements - the natural environment and racial groups (Indians and Blacks). Political centralization and the creation of a national institutional network made it possible for Brazil to be consolidated and conceived of as a Nation, especially through the intellectual efforts of artists and scientists. In the work of Jackson Turner, the imagined community is constructed from the grassroots, through the efforts of free, common men in their confrontation with the natural environment. The duel between Man and Nature, in which each element transforms and is transformed by the other, creates a uniquely American product. It is a new cultural type distinct from its European counterpart. This idea of identity is characterized by the Frontier experience and creates a society marked by movement, conflict and the eternal pursuit of material improvement and Progress.