The geographic diversity of the places grappling with the trade-offs highlights how pervasive the connections are between natural resources, health and economic opportunity.

In the vast farmlands of central California, day care centers have to take account of pesticide-spraying schedules. The local government’s revenues on the Fort Berthold Indian Reservation in North Dakota have grown to $330 million from $20 million over the last 15 years because of vast fossil fuel reserves that can now be pumped from the ground using fracking. National forests 400 miles away can be clouded with haze produced by a coal-fired power plant near Houston.

The rollbacks touch air, water, chemicals and climate

No parts of the federal government during the Trump era have been more aggressive in rolling back rules than the Environmental Protection Agency and the Interior Department, which between them regulate much of the intersection between the environment and the economy. Together their rule changes have touched nearly every aspect of environmental protection, including air pollution caused by power plants and the oil and gas industry, water pollution caused by coal mines, and toxic chemicals and pesticides used by farmers nationwide.

In short, what is at stake is the quality of the air we breathe and the food we eat, the cleanliness of the rivers that flow past us, and the pace at which the climate is changing. Two years after Mr. Trump took office, the policy shifts are not nearly complete; dozens of other rules have been targeted for rollback.

After decades of legislation and regulation, the environment in the United States continues to get cleaner. What has changed under Mr. Trump in most cases is the pace of improvement, which has been slowed in a number of key areas compared to what it would have been if the Obama rules had been preserved.

The decline of coal has not been stopped

If there is a single industry that has been at the center of the fight — both during the Obama expansion of rules and the Trump rollbacks — it is coal. Mr. Obama targeted the industry as a way to combat climate change. Mr. Trump has defended and promoted it as part of his populist political and economic strategy.

Mr. Trump’s approach has been to slow demands for further steps to curb air and water pollution caused by coal-burning power plants.