The existing research of inter-jurisdictional policy implementation relies on aggregated data from established or completed networks, which cannot discern individual level heterogeneity among policymakers in earlier stages of interlocal collaboration. Further, scholars have difficulties to isolate collaborative mechanisms by the nature of interdependency of network data. Therefore, I conduct a conjoint experiment of U.S. municipal officials to overcome these challenges, in which the design compared three fundamental theories: rational choice, political homophily, and social capital, to predict willingness to collaborate. The results indicated that all three theories affect officials’ decisions to collaborate in implementing sustainability programs jointly, but political homophily has relatively less explanatory power than the other two. This study revealed further the different priorities between elected officials and city managers’ choices to collaborate. An additional subgroup analysis of party affiliation suggested that Republicans are willing to sacrifice self-interests to balance costs with their co-partisan collaborators. Overall, this experimental approach offers new opportunities to study interlocal collaboration.

Figure 3: Subgroup analysis by party affiliation.