The experiences of cross-border cooperation (CBC), undertaken not only in Europe but throughout the world, have enabled areas to gain greater importance in recent decades at an international level, showing potential for integrative functions and joint development as exemplified by several CBC projects. The present paper assesses the impact of CBC projects by analyzing a protocol established in 2013 between the cities of Elvas and Badajoz, which induced the creation of the Eurocity Elvas-Badajoz. The paper kicks off with a critical review on territorial factors for success in CBC areas, considering the analysis of several case studies throughout Europe. The lessons learned, taken from the analyzed case studies, and the identified territorial success factors were used as assessment points for the investigation of the target study area, the Eurocity Elvas-Badajoz. The investigation explores public participation perceptions towards the identification of what changes with respect to standards of life with the CBC project, providing the current state of affairs and identifying where to place efforts in order to reach sustainable development for the region. While being a transition area, it presents several opportunities for growth. These opportunities have not yet been object of analysis and debate with respect to lasting, sustainable successful growth. The present research enables the identification of several territorial factors for success in the study area, such as the connectivity/movement between cities and strong political commitment. From the identified critical factors, it was possible to highlight the importance of public transportation as a priority for achieving success in this CBC project.