President Joe Biden has announced the toughest restrictions on vehicle exhaust emissions ever introduced in the United States in an effort to accelerate the auto industry's transition to electric cars.
The goal includes a 56% electrification of all new U.S. vehicles sold by 2032 — a huge increase from current levels.
As a concession to automakers, the target was softened from last year's draft.
But the Biden administration says it will cut planet-warming gases even more dramatically.
According to the Environmental Protection Agency, Wednesday's regulation will prevent 7 billion tons of carbon dioxide emissions over the next 30 years.
The new measure limits the amount of pollutants allowed from vehicle emissions annually. Car makers who do not meet the new standards will face heavy fines.
Companies can produce gasoline-powered vehicles as long as they constitute a shrinking percentage of their total product line.
The US is taking a more moderate approach than the European Union and the UK, which will ban all sales of petrol-powered cars from 2035.
UK Prime Minister Rishi Sunak announced last year that the British ban would be delayed by five years from its original deadline of 2030.
The U.S. auto industry pointed to slower electric vehicle (EV) sales growth last year when it vetoed draft rules that would have ensured that 67% of all new cars sold by 2032 were electric vehicles.
EVs accounted for less than 8% of all new car sales last year.
The Alliance for Automotive Innovation, a trade group representing the car industry, welcomed the slower pace of rollout but said the target was still “extraordinarily ambitious”.
Environmental groups broadly welcomed the move, although some activists expressed disappointment.
But the rules are expected to face legal challenges from the oil industry and Republican-led states. It will ultimately be decided by the Supreme Court.
The policy highlights the political tightrope Mr. Biden must walk.
As he runs for re-election against his Republican rival, Donald Trump, the president is trying to win over auto workers in the key state of Michigan while taking action to address climate change, a key issue for many Democrats.
Mr Trump has vowed to roll back environmental regulations passed by Mr Biden if he wins in November.
Carolyn Leavitt, a spokeswoman for the Trump campaign, said the rules would “destroy the American auto industry while forcing Americans to buy more expensive cars they don't want and can't afford.”
The average selling price of an EV was $53,500 last year, $5,000 more than gasoline-powered cars, according to trade publication Kelly Blue Book.
The average annual salary in the US is around $59,000.
Mike Johnson, the Republican speaker of the House of Representatives, criticized the policy as “another aggressive, anti-energy war that will limit consumer choices, raise costs on American families and destroy automakers.”