Historically, citizenship has been a gatekeeper to political and social rights within communities, as entitlements of membership were closely connected to gender, race, and class. Nowadays, citizenship is a symbol of equality within states as much as a marker of inequality among states. It is (1) a defining feature of the international state system, which both reflects and reinforces inequalities of wealth and opportunity around the world, and (2) a tool for social closure, through which states determine who belongs to the group that can share common entitlements and who, by contrast, are excluded from them. These two characteristics of citizenship are central to understanding the citizenship-migration nexus: whereas the promise of equality represents a strong driver for migrants to acquire citizenship in their destination states, the different opportunities attached to citizenship of different countries encourage migration of individuals from less privileged parts of the world and enable mobility for those with a citizenship status in the more advantageous countries.

Jelena Džankić and Maarten Vink, Citizenship & Migration, Introduction to Migration Studies, 2022.