The Trump Administration Rolled Back More Than 100 Environmental Rules. Here’s the Full List.

Over four years, the Trump administration dismantled major climate policies and rolled back many more rules governing clean air, water, wildlife and toxic chemicals.

In all, a New York Times analysis, based on research from Harvard Law School, Columbia Law School and other sources, counts nearly 100 environmental rules officially reversed, revoked or otherwise rolled back under Mr. Trump. More than a dozen other potential rollbacks remained in progress by the end but were not finalized by the end of the administration’s term.

“This is a very aggressive attempt to rewrite our laws and reinterpret the meaning of environmental protections,” said Hana V. Vizcarra, a staff attorney at Harvard’s Environmental and Energy Law Program who has tracked the policy changes since 2018. “This administration is leaving a truly unprecedented legacy.”

The bulk of the rollbacks identified by the Times were carried out by the Environmental Protection Agency, which weakened Obama-era limits on planet-warming carbon dioxide emissions from power plants and from cars and trucks; removed protections from more than half the nation’s wetlands; and withdrew the legal justification for restricting mercury emissions from power plants.

At the same time, the Interior Department worked to open up more land for oil and gas leasing by limiting wildlife protections and weakening environmental requirements for projects. The Department of Energy loosened efficiency standards for a wide range of products.

In justifying many of the rollbacks, the agencies said that previous administrations had overstepped their legal authority, imposing unnecessary and burdensome regulations that hurt business.

“We have fulfilled President Trump’s promises to provide certainty for states, tribes, and local governments,” a spokeswoman for the E.P.A. said in a statement to The Times, adding that it was “delivering on President Trump’s commitment to return the agency to its core mission: Providing cleaner air, water and land to the American people.”

But environmental groups and legal analysts said the rollbacks have not served that mission.

All told, the Trump administration’s deregulatory actions were estimated to significantly increase greenhouse gas emissions over the next decade and lead to thousands of extra deaths from poor air quality each year.

Many of the rollbacks have been challenged in court by states, environmental groups and others, and some have already been struck down. In the final days of Mr. Trump’s term, a federal appeals court overturned a plan to relax Obama-era restrictions on carbon dioxide emissions from coal- and natural gas-burning power plants, arguing that the agency misinterpreted its obligation under the Clean Air Act to reduce carbon pollution.

The Times identified nearly a dozen more rules that were initially reversed or suspended by the Trump administration but later reinstated, often following lawsuits and other challenges. They are summarized at the bottom of this page, and are not counted in our overall tally.

President-elect Biden is expected to undo several of the rollbacks through executive orders soon after assuming office on Jan. 20, including cancelling the permit for the controversial Keystone XL pipeline and rejoining the Paris climate change agreement. The Democrat-controlled House and Senate could help nullify several more Trump-era rules through a once-obscure law that grants Congress the power to review regulations recently adopted by federal agencies. But other rules will be more difficult to change, requiring months — or even years — of work to repeal and replace.

Below, we have summarized each rule that was targeted for reversal.