When Congress passed the Clean Air Act in 1970, climate change wasn't on anyone's mind. Yet under an Obama-era decision known as the "Endangerment Finding," the Environmental Protection Agency has claimed authority under the act to micromanage large parts of the American economy in the name of combating global warming. A new Trump administration proposal to reverse the Endangerment Finding returns the Clean Air Act to its original purpose, marking the end of a failed effort to control the climate through executive fiat.