The carbon intensity of electricity generation—measured in emissions per megawatt-hour—differs dramatically across the United States, according to federal data compiled by the Institute for Progress. States that burn large amounts of coal and petroleum, such as West Virginia, Kentucky, and Wyoming, top the dirtiest list, while Vermont leads the cleanest with essentially 100% renewable generation, mostly hydropower. The map reflects power produced within each state, not consumed, so states like Wyoming that export much of their electricity can have a cleaner consumption profile than their generation suggests.
Nationally, the power sector has made significant strides: greenhouse gas emissions fell roughly 40% between 2005 and 2024, as coal plants shut down and were replaced by natural gas and renewables. Only Idaho and Vermont saw no improvement in carbon intensity over that period, though both already had very clean grids. However, the article notes that the Trump administration's rollback of federal climate policies, combined with a gas-power boom driven by data-center demand, could slow or reverse this trend. The source emphasizes that states now bear greater responsibility for continuing the clean-energy transition, as federal support wanes.