Based on a survey of 2010 citizens in four large metropolitan areas in Switzerland, the analysis presented in this article shows that spatial mobility of citizens across municipal borders leads to an up-scaling of their territorial identities at the level of the city-region. On the one hand, this results in a favourable attitude towards encompassing institutions at the city-regional scale. On the other hand, given the high degree of institutional fragmentation prevailing in Swiss city regions, strong city-regional orientations lead to a delegitimisation of the local political system. Without adequate reforms of the territorial institutional framework the ongoing growth and functional integration of city-regional spaces will lead to political alienation and increasingly challenge the democratic legitimacy of the local state in Switzerland. More generally, the article shows that the long-running debate on metropolitan governance should focus, more thoroughly than in the past, on issues of citizenship and democratic legitimacy.