In summer 1987, the U.S. president, Ronald Reagan, visited West Berlin and gave a speech in front of the Brandenburg Gate, addressing the leader of the Soviet Union: “Mr. Gorbachev, tear down this wall!” Two years later, as a result of the peaceful uprising of people in the former GDR, the Berlin Wall, a monument of division and block confrontation, came to the end of its existence. After the fall of the Berlin Wall, there was a widespread illusion that hard borders could become more porous and ultimately lose their significance. At the same time, the trend of globalization was unfolding, with an unprecedented increase in cross-border mobility and transactions. Moreover, technological developments and innovation have ultimately facilitated the view that connectedness is one of the signs of our era, leading to statements such as “the world is flat.” However, borders have proved to be resilient institutions, as states have adapted and reinvented border controls in several ways. First, states have responded to new challenges by hardening their territorial boundaries through border fortifications. Second, governments have shifted border control to third countries by using tools such as visa policies or readmission agreements. Third, nation states have designed “smart borders” through biometric passports, shared databases, and digital surveillance technologies. Lastly, de-facto borders show that clearly delimited boundaries can be attractive to countries, even in regions with limited statehood. Our special issue traces these transformations and reveals how states are digitizing, reinforcing, and externalizing border controls in response to new challenges.