The extent of political fragmentation of metropolitan areas impedes effective land use planning in many countries, and thus contributes to the phenomenon of urban sprawl. For some metropolises in the United States and Europe, strategic interaction between local policymakers codetermines the implementation of local planning policies. However, previous empirical analyses of this phenomenon have usually assumed interdependence in planning decisions to be confined to neighbouring jurisdictions. This is a common simplification in research on diffusion in public policies. Proceeding on the assumption that municipal zoning decisions are subject to competition between municipal authorities trying to attract new residents, I suggest an alternative conceptualisation of location-choice competition in Tiebout-like economies: the correlations of out-commuting patterns serve as a proxy for the degree to which municipalities are competitors for mobile residents, irrespective of their contiguity. Spatial autoregressive models, estimated on the basis of a large panel of fine-grained zoning data, reveal that zoning decisions in the Canton of Zurich, Switzerland's most dynamic metropolitan area, are indeed subject to such interdependence.