Milestones in State Climate Policy

The federal government's interventions in climate policy have been erratic, driven by political polarization and alternating control of the White House. In contrast, state governments have engaged in steady campaigns to reduce carbon emissions.  Some people seem to think this has been a recent innovation, but it has now been ongoing for a generation.  Here are some the key milestone along the way, closing with Trump's pledge to bulldoze state policies that don't fall in line with his priorities.