This paper documents the evolution of US carbon emissions and discusses the main factors that contributed to the historical carbon emissions rollercoaster. We divide the discussion into four periods – up to 1920, 1920-1960, 1960-2005 and after 2005. For each period, we discuss the main drivers of national carbon emissions. We then discuss trends in carbon emissions in the electricity sector. Electricity sector emissions were initially very small, but would become the largest source of US carbon emissions over the period 1980-2015, and the largest contributor to decarbonization since 2007. In the final section, we distill lessons from the U.S. experience that may inform decarbonization strategies in developing economies.