The biggest producer of electricity in the U.S. is
natural gas. It has been the largest source of electricity generation for several years now, accounting for around 40% of the total electricity production in the country.
Natural gas is used in power plants because it burns more cleanly than coal, which makes it a popular choice. The second-largest source is
nuclear power, followed by
coal (although coal's share has decreased significantly in recent years), and
renewable sources like wind and solar are rapidly growing as well.