The literature on interlocal sustainability has acknowledged that the resources and authority of state governments influence the collaborative sustainability policy actions of local governments. However, there is an absence of empirical evidence that shows how this influence varies across the environmental protection, economic development, and social equity pillars of sustainability. This study uses data from a 2015 national survey of U.S. cities to shed light on the connection between state-level interventions and regional partnerships across the three primary sustainability policy dimensions. With an understanding gleaned from the concept of contested federalism, this analysis employed Bayesian techniques to examine how state fiscal support for sustainability, along with fiscal and functional decentralization in state systems, affect municipal collaborative policy efforts. The findings suggest a positive link between supportive state-level endeavors and local-level collaborations. However, state influences can have different implications across the three pillars of sustainability.