We examine the determinants of the current level of formal sovereignty of a set of 104 small island and coastal economies (SIEs), using a large database of geographical and political characteristics. Using simple econometric tests, we find that the larger the population size (current or historical) of the SIE and the greater the distance from its metropolitan power (Euclidean distance or maritime distance), the higher its level of sovereignty. This result is robust to the introduction of other potential geographical factors (latitude, longitude, area, insularity, EEZ area). These results are consistent with those of a model dominated by centrifugal forces, where the level of sovereignty can be explained, at least in part, by the costs of producing and providing public services, both for the metropolitan power and the SIE, and by the heterogeneity of preferences between the two. The specificity of the territories for which France is the metropolitan power is reinforced. These territories have, on average, a significantly lower level of sovereignty than the others. Our results show that this remains the case when the population size of the SIEs and the distances separating them from their metropolitan power are taken into account in the analysis of all 104 SIEs. The SIEs for which the United Kingdom is the metropolitan power, for example, do not show this specificity. This importance of the identity of the metropolitan power could be linked to the type of state and the way in which it intervenes in the affiliated SIEs (centralising or decentralising, social or liberal state, etc.).