Security concerns about immigration are on the rise. Many countries respond by fortifying their borders. Yet little is known about the influence of border security measures on perceived threat from immigration. Borders might facilitate group identities and spread fear of outsiders. In contrast, they might enhance citizens’ sense of security and control over immigration. We test these claims using survey experiments run on a quota sample of over 1000 Americans. The findings show that allocating more government resources to border security increases desired levels of immigration. This effect is likely driven by a sense of control over immigration, induced by border security measures even when the number or characteristics of immigrants remain unchanged. Our findings suggest that border controls, which are widely considered as symbols of closure and isolation, can increase public support for immigration.