However, even when innovation actors are in proximity, the presence of an international border is a barrier for collaboration, one that is increasing in recent years. For many regions, there are a number of reasons why collaborating with an international neighbour makes sense for both sides. For innovation purposes, the definition of the “functional” area for cross-border policy requires some assessment of both the innovation relationships that are (or could be) relevant, as well as the other functional ties and institutional arrangements.