Where does America get all of its electricity from?

Anyone who’s visited the Hoover Dam knows it helps keep the lights on in Las Vegas, as well as other cities throughout Nevada, California, and Arizona. But when you flip a light switch, do you know what’s powering the bulb? If the answer is coal, that could change over the next few years. President Obama and the Environmental Protection Agency recently unveiled the Clean Power Plan, which aims to reduce CO2 emissions from U.S. coal-burning power plants — the country’s biggest source of those emissions — by 32 percent by 2030. Carbon pollution is already on the decline, but the EPA wants to speed up the process. States have until 2018 to propose strategies on how to accomplish this and until 2022 to put them in motion. But not all states are on equal footing when it comes to the changes that need to be made to reduce the emissions. Compare Kentucky and its neighbor Tennessee. While Kentucky gets 92 percent of its energy from coal (petroleum, natural gas, and hydro making up the rest), Tennessee has a more diverse power portfolio: Coal provides 46 percent, and hydro, natural gas, biomass, and nuclear are the other power sources.