For 75 years, petroleum has been the energy source that has powered the U.S. more than any other. That’s about to change.

By the end of the decade, natural gas likely will surpass oil for the first time after the gap all but disappeared in 2025. This seismic shift will end a chapter that began in 1950, when petroleum ended the longstanding reign of another fossil fuel: coal.

“I say we probably cross that threshold within the next couple years, and by 2030, we will have a big lead on petroleum,” Toby Rice, CEO of top U.S. gas producer EQT Corp., said in an interview.

The transition from America being a nation powered by oil to one running primarily on gas shows how much the economics of cheap gas has reordered parts of the energy sector and pushed out competing fuel sources.

The rise of wind and solar as significant contributors to U.S. electricity generation has also aided the development of gas-fired power plants, as gas facilities can ramp up and down more rapidly than coal and nuclear generators when intermittent renewable power drops.

Notably, the positioning of gas as a top U.S. energy source doesn’t account for the explosive growth of U.S. liquefied natural gas. The U.S. is already the world’s largest exporter of LNG, and shipments are set to roughly double by the end of the decade. Shell predicts U.S. feedgas for LNG plants will make up 23% of total U.S. gas production by 2035, according to its annual LNG outlook.