Many view nationalist ideologies and national identities across Europe as the outgrowth of economic, social, and political modernisation in the 19th and early 20th centuries. Yet, there are few spatio-temporally disaggregated and continent-wide tests of the relationship between modernisation processes and nationalism. More importantly, it is theoretically unclear whether modernisation led to national cohesion and stabilised Europe’s multi-ethnic states or whether it destabilised them by fueling non-state nationalisms and separatist mobilisation.
In this paper, we use the gradual expansion of the European railway network 1816-1945 to investigate how this key technological driver of modernisation affected ethnic separatism. Combining new historical data on ethnic settlement areas, conflict, and railway construction, we test how railroads affected separatist conflict and successful secession as well as independence claims among peripheral ethnic groups. Difference-in-differences, event study, and instrumental variable models show that, on average, railway-based modernisation increased separatist mobilisation and secession. Exploring causal mechanisms, we show how railway networks can either facilitate mobilisation by increasing the internal connectivity of ethnic regions or hamper it by boosting state reach. In line with our theoretical framework of center-periphery bargaining, separatist responses to railway access concentrate in countries with small core groups, weak state capacity, and low levels of economic development as well as in large ethnic minority regions. Overall, our findings call for a more nuanced understanding of the effects of European modernisation on nation building.