Demographic engines at work: Disentangling natural and migratory dynamics at local scale for Italian and foreign citizens

Italy’s demographic decline is marked by strong spatial heterogeneity and an increasing role of immigration. However, local-scale dynamics and the interaction between natural and migratory components—especially across citizenship groups—remain understudied. We analyze annual population change in Italian municipalities between 2001 and 2018, comparing Italian and foreign residents, and explicitly considering the acquisition of Italian citizenship by nonnative residents. We use municipality-level data from Italian National Statistical Institute’s demographic balance reconstruction (2001–2018), covering nearly 8000 municipalities. Adapting Webb’s method, we classify each municipality according to the sign and magnitude of its natural and migratory balances, incorporating naturalizations into the migration component. The results reveal significant spatial heterogeneity within the Italian population, which is, by contrast, largely absent among the foreign population. Overall, migration emerges as a pivotal factor in shaping demographic trends for both groups. Migration plays a central role in shaping demographic outcomes, but its effects differ markedly across space and citizenship groups. Among nonnative residents, growth is largely sustained by mobility rather than natural increase. This is the first study to apply the Webb method at full municipal scale in Italy, distinguishing native and foreign populations and accounting for citizenship transitions. It offers important insights into the role and impact of the foreign population on Italy’s demographic evolution, challenging several prevailing assumptions.