For the first time in U.S. history, natural gas has become the top source for electricity generation, overtaking coal.

The Associated Press reports on how dramatic a change this is:

About 31 percent of electric power generation in April came from natural gas, and 30 percent from coal, according to a recently released report from the research company SNL Energy, which used data from the Energy Department. Nuclear power came in third at 20 percent.

… Federal data shows that in April, the amount of electricity generated with natural gas climbed 21 percent compared with April 2014, and the amount generated with coal fell 19 percent. In April 2010, 44 percent of electric power generation came from coal and 22 percent from gas, according to SNL Energy.

This monumental shift has its roots in private-sector innovation. The combination of horizontal drilling and hydraulic fracturing has created an American energy boom over the past decade. As the AP notes, domestic natural-gas production has risen 30 percent since 2008, making the United States the world’s top producer.

As America relies more on natural gas for its electricity, that’s great news for the environment. As IWF has repeatedly noted before, natural gas is the cleanest fossil fuel in existence; coal about twice as carbon-intensive, while oil releases up to 30 percent more C02 emissions as natural gas. Already, the United States is enjoying its cleanest air in decades.