States around the world are fortifying their international borders at unprecedented rates. While only seven states had fortified their borders with walls or fences as of the end of World War Two, this number has now grown to more than 75. Why do states build walls on their international borders? While states may build walls to ameliorate the consequences of cross-border economic inequalities and to defend against transnational security threats, we suggest that another compelling logic stems from domestic politics and leaders’ desire to remain in office. Building on assumptions furnished by diversionary theory, we argue that national political leaders at risk of losing office are incentivized to implement popular policies, such as border wall construction, hoping that doing so will prompt a domestic rally effect. To test this argument, we assemble a global dataset of leader-years and find that politically insecure leaders are more likely to be seen to start and continue border wall construction.