Citizenship laws and international migration in historical perspective

We investigate the origin, impact and evolution of the legal institution of citizenship. We compile a dataset across countries of the world from the 19th century, which documents how citizenship laws have evolved from the common and civil law traditions. Contrary to the predictions of legal theory, we show that the original, exogenously-given citizenship laws did not matter for migration flows during the early, mass migrations period. After WWII, citizenship-granting institutions are no longer exogenous as they are shown to be determined by international migration flows, border stability, the establishment of democracy, the welfare burden, cultural factors, and colonial history.