Why Physical Barriers Backfire: How Immigration Enforcement Deters Return and Increases Asylum Applications

Abstract

What, if any, effect do physical barriers have on cross-border population movements? The foundational claim that barriers reduce migration flows remains unsupported. We conceptualize barriers as a tool of immigration enforcement, which we contend is one form of state repression. State repression could reduce mobilization (reduce immigration), have no effect on mobilization (barriers as symbolic political tools), or increase mobilization (backfire). We evaluate the relationship between barriers and cross-border population movements using a global directed dyad-year dataset for the 1990–2016 time period of all contiguous dyads and nearby non-contiguous dyads. Using instrumental variables, we find that physical barriers actually increase refugee flows, consistent with the “backfire effect” identified in research on United States immigration enforcement policies on its Mexican border. Furthermore, we find that state repression (immigration enforcement) creates this “backfire effect” via a “sunk costs” problem that reduces movements of people and increases movement of status from migrant to refugee.