Аннотация:This article is a critique of two different types of essentialisms that have gained widespread acceptance in places as distant as the U.S.-Mexico border and different Mercosur frontiers. Both essentialisms rely on metaphors that refer to the concept of "union," and put their emphasis on a variety of "sisterhood/brotherhood" tropes and, in particular, the "crossing" metaphor. This kind of stance tends to make invisible the social and cultural conflict that many times characterizes political frontiers. The article wants to reinstall this conflictive dimension. In that regard, we analyze two different case studies. The first is the history of a bridge constructed between Posadas, Argentina and Encarnación, Paraguay. The second is the community reaction toward an operation implemented by the Border Patrolin 1993 ("OperationBlockade") in a border that for many years was considered an exemplar of the "good neighbor relationships" between Mexico and the United States, the frontier between El Paso and Ciudad Juárez.
