Electricity generators that use fossil fuels continue to be the most common sources of electricity generation in most states. In all but 15 states, coal, natural gas, or petroleum liquids were the most-used electricity generation fuel in 2017. Since 2007, the number of states where coal was the most prevalent electricity generation fuel has fallen as natural gas, nuclear, and hydroelectricity have gained market share.
In 2017, coal provided the largest generation share in 18 states, down from 28 states in 2007. Natural gas had the largest share in 16 states, up from 11 in 2007. Petroleum remained the largest generation share in only one state—Hawaii—providing 62% of the state’s electricity generation in 2017. For the U.S. as a whole, natural gas provided 32% of total electricity generation in 2017, slightly higher than coal's 30% share.