Public opinion in favor of regional unification is usually seen as key for successfully implementing such integration projects. We argue that, as a positive externality, it can also foster support for migration outside that region. Focusing on the case of Europe, we claim that citizens who are more supportive of EU unification tend to be more open, globalized, and cosmopolitan, which may be linked to more support for migration from outside of Europe. Our empirical analysis combines observational and experimental data. First, results from macro (country) and micro (individual) level analyses using the European Social Survey strongly support our theory. Second, we delve deeper into the underlying mechanism based on a survey experiment conducted in Germany. This evidence suggests that priming people about a shared European history also increases support for migration from outside the EU. This research significantly contributes to our understanding of how people's views of migration are formed, and it sheds new light on the consequences of regional integration projects such as the EU.
