Schmid Comparative Migration Studies (2020) 8:25 Conclusion In this article, I have formulated a theory of the structural logics shaping immigration policies and citizenship policies – the logic of markets, the logic of nations, as well as the legal and the democratic logic of the liberal state (cf. Hampshire 2013). Based on this theory I have introduced a novel typology – called The National Boundary Regimes Typology – that focuses on the regulation of two fundamental social boundaries of modern nation-states: territorial boundaries (Immigration Regime Openness, IRO) and membership boundaries (Citizenship Regime Inclusiveness, CRI). I have made four main empirical observations on the two-dimensional policy space determined by the different degrees of IRO and CRI, most of which are in accordance with the specified theoretical framework. First, a Categorical Principal Component Analysis (CATPCA) based on a combination of original and existing panel data across 23 liberal democracies from 1980 to 2010 has confirmed that IRO and CRI are internally consistent and statistically distinct dimensions. I have thereby provided empirical evidence for the existence of these dimensions – something which is lacking in the literature (Koopmans 2013, p. 696). The finding that there is no internal trade-off in immigration policies regarding different migrant groups suggests that economic liberalism – embodied in the economic logic of the market – and political liberalism – embodied in the legal logic of the liberal state – are rather complementary than contradictory forces in determining the openness of immigration policies. Similarly, the finding that citizenship policies are coherent suggests that the interaction of the democratic logic of the liberal state with the cultural logic of the nation leads to a single empirical dimension of inclusiveness. Often seen as something different, civic integration requirements are part of this singular statistical continuum. Second, the distribution of cases over the four ideal-typical policy configurations from 1980 to 2010 has shown that more and more cases combine relatively liberal immigration policies with relatively liberal citizenship policies; they are open-inclusive and thus have a liberal-cosmopolitan quality. This demonstrates that the ‘liberal paradox’ (Hollifield 1992, 2004) has been increasingly resolved, and the ‘Liberal Model’ rather than the ‘Market Model’ (Boucher and Gest 2018) has become more prevalent. Third, the aggregate levels of both IRO and CRI follow overall liberalising trajectories with convergence in immigration and non-convergence in citizenship. However, the liberalisation in immigration policies stops in 1996 and fluctuates thereafter. This trend indicates that the constraints by globalization, which should lead to greater openness, are limited. The non-convergence in citizenship policies highlights national pathdependencies. This is confirmed by a disaggregated analysis showing the evolution of policies by country (see Additional file 1). The analysis has also shown a restrictive turn in citizenship policies during the 2000s, which is concurrent with expectations in the literature. The novel finding in this article is that another restrictive turn has already taken place during the 1990s. This suggests that also illiberal and exclusive forces have been at work in the realm of citizenship. Fourth, this article has also shown that there is an increasingly positive correlation between IRO and CRI. This stands in contrast to the widespread assumption that there is a general trade-off or negative correlation between the territorial and membership dimensions of national boundary regimes (e.g. Ruhs 2013; Walzer 1983, ch. 2). This result suggests that the different structural logics do not remain distinct; they converge or coalesce over time. Page 18 of 20