Abstract:Many diverse actions can be taken to reduce greenhouse gas (GHG) emissions. Increasingly in the United States, policy-makers at sub-national levels are setting emission targets and implementing plans for sector-specific GHG reductions. In this paper, local, state, and regional policy actions in the US are inventoried and analyzed as to their potential effect on national emissions. The realization of all existing sub-national initiatives, as of September 2007, could stabilize US emissions at 2010 levels by the year 2020. The scale of these many decentralized mitigation actions, and their tendency to follow consistent steps, provide a counterpoint to oft-cited drawbacks of decentralized environmental policy. It also indicates that the US has been more committed to climate change mitigation than is generally acknowledged.