A 90% clean grid nearly eliminates emissions from the U.S. power sector by 2035, generating health and environmental benefits while decreasing deaths attributable to electricity generation. A 90% clean grid reduces carbon dioxide emissions by 88% through 2035. It also reduces exposure to fine particulate matter by reducing nitrogen oxide emissions by 96% and sulfur dioxide emissions by 99%. As a result, a 90% clean grid avoids more than $1.2 trillion in health and environmental costs, including 85,000 avoided premature deaths, through 2050. When environmental and health costs are considered, a 90% clean grid is the lowest-cost option.