This roundtable raises crucial questions about citizenship, national communities, popular sovereignty and the debates that have informed the political and intellectual relationship between Mexico and the United States from the nineteenth century to the twenty-first century. These themes revolve around the research and trajectory of Professor Erika Pani (Colegio de México). Drawing on a transnational and comparativist lens, the panelists will engage the particularities, but also the commonalities, that surround and inform the U.S. Civil War, Mexico’s War of the Reform, and the Mexican Revolution. Drawing on these and other episodes, the participants are asked to consider what ultimate difference does a comparative worldview make given the historical animosities between two neighbor republics that are always in tension with one another? Moreover, how is the comparative study of the 19^th century in Mexico and the U.S. different from Eric Hobsbawm’s work on the Age of Revolution or the Global History movement of the 1990s and early 2000s? These queries also invite critical reflection on how borderland communities, far removed from Mexico City and Washington D.C., experienced the formation of these two "nations" or "national communities."