This note presents an account of transboundary basins on a global and regional scale throughout history. The authors introduce the special section on transboundary basins, presenting their constant increase and profound complexity. Regions & Cohesion has shown a permanent interest in this subject, from its first publications and, in particular, with the 2014 special issue that addressed different theoretical, methodological, and case studies in different continents. The three readings that make up this section address contemporary water border contexts and Mexico–U.S. policy where multi- and transdisciplinary challenges continue.