Kindred spirits or intergovernmental competition? The innovation and diffusion of energy policies in the American states (1990-2008)

The innovation of environmental policies and their subsequent diffusion throughout the American states has been the subject of significant academic attention. Using an event history analysis, a traditional geographic model for policy diffusion is tested against a model where states learn from peer groups, defined by political culture. There is evidence for state learning within peer groups but less support for diffusion across state borders. Policy characteristics, environmental conditions, economic resources, and political constraints and opportunities are tested as drivers of differences in policy adoption. More than any other factor, politics and political culture explains the adoption of energy and climate-change policies. These results also suggest that restricted models that test geographical mechanisms of policy diffusion likely omit important characteristics that are correlated across states, leading to biased findings regarding the geographical state diffusion models in the extant literature.