In this study, we examine the political effects of the breakup of East Prussia into what is today Poland, Russia, and Lithuania. We expect that East Prussian legacies of nationalist and conservative political preferences persist in the respective partitions of Poland, Russia, and Lithuania. We find that there is no pattern of persistence in the Polish partition of former East Prussia, whereas East Prussian persistence appears to be robust in the Lithuanian and Russian partitions. In the context of forced migration, comparative human capital between outgoing refugees (Germans) and incoming settlers (Soviets, Poles) predicts patterns of long-run political development. Hence, higher literacy rates of incoming settlers in the Russian partition (Kaliningrad) predict higher levels of support for conservative and nationalist political parties. The opposite is observed in the Polish partition. The persistence of East Prussian legacies in Eastern Europe relates to settler literacy.