Already, the 21st century has seen an unprecedented increase in cross-border movements of people, goods, information, and financial capital. Numerous incentives and facilitators have expanded international interconnectedness and mobility, so altering the conventional nature and functions of state borders, as captured by the “new mobilities” paradigm. Yet the weaponization of global economic interdependencies and other trends towards deglobalization mean there is now a growing pressure on governments to re-establish the conventional attributes of borders. Against the current mobility and security backdrop, this collection of articles takes stock of the meaning, roles, and practices of border activities. Now is the moment to consider the special role that borders perform as an institution of state security in a contemporary world exposed to massive international flows of people and goods, as well as technologically-driven control and management systems.