Political homophily and collaboration in regional planning networks

We study the extent of political homophily-the tendency to form connections with others who are politically similar-in local governments' decisions to participate in an important form of intergovernmental collaboration: regional planning networks. Using data from a recent survey of California planners and government officials, we develop and test hypotheses about the factors that lead local governments to collaborate within regional planning networks. We find that local governments whose constituents are similar politically, in terms of partisanship and voting behavior, are more likely to collaborate with one another in regional planning efforts than those whose constituents are politically diverse. We conclude that political homophily reduces the transaction costs associated with institutional collective action, even in settings where we expect political considerations to be minimal.