In the lines of this book, it will be possible to highlight the main contributions of Geography in the problem that was experienced between the years 2016- 2017 in terms of the commercial impact on the microcenter sector of the city of Posadas product of social and economic flows between Posadas (Misiones, Argentina) and Encarnación (Paraguay). From Social Geography it is necessary to take into account the concept of "Cross-border Flow". According to Reitel B and Zander P (2013) the adjective cross-border applies a priori to any movement, any relationship across a political boundary between two states. However, the notion of cross-border is deeply linked to the notion of proximity, relations between two states are generally transnational.90% of the movement of people in the international crossing Posadas-Encarnación is carried out under the migratory regime of Neighbourhood Border Transit, that is to say, between Posadas and Encarnación citizens. This constant circulation of people with different purposes (commercial, family, work, social, study, etc.) across the border is shaping spaces that could be called "cross-border".