There are two central questions about the Southeast region in this report: how does the physical energy infrastructure in the Southeast region need to evolve to enable a low carbon transition, and what are key decarbonization opportunities and challenges in the Southeast from a societal perspective? Answers to these questions can support regional stakeholders’ efforts to develop a shared vision of pathways to deep decarbonization, and advance discussions in states across the region. This study explores these questions in three sections. The first section provides context about the national pathways to deep decarbonization, which provides the basis for a Southeast regional exploration. The second section lays out the regional analysis approach and provides an in-depth exploration of Southeast-specific topics. The final section considers broader implications of the physical changes for policymakers, long-term planners, and stakeholders within the region.