Exogenous shocks can place local governments under financial strain by reducing revenues or creating unforeseen spending obligations. In response, governments may either mobilize new resources or adjust the allocation of existing ones. Such choices can generate territorial inequalities, whereby individuals with identical legal rights receive different levels of public service depending on where they live.

This article examines these dynamics through the case of foster care services in France (ASE, aide sociale à l’enfance). Following the 2015 European migrant crisis, the ASE system experienced the arrival of new beneficiaries—unaccompanied migrant minors—whose support required substantial additional spending. We analyze how French départements, which are responsible for ASE services, adjusted their expenditures in the face of this shock. In particular, we investigate the heterogeneity of these responses and assess whether it can be explained by pre-existing conditions—such as financial robustness—or by the political orientations of local elected officials.