New York City produces twice as much trash as any other mega-city on Earth, according to a recent study. The Environmental Protection Agency has described Brooklyn's Gowanus Canal as "one of the nation’s most extensively contaminated water bodies." And air pollution, coming largely from transportation and construction, remains a threat to residents.

But before the EPA formed in 1970, pollution in NYC was even worse.

Soon after the EPA's founding, the agency dispatched 100 photographers to capture America's environmental issues in a photo project called Documerica. It shows what the US, from California to Ohio to New York, looked like from 1971 to 1977. Of the 81,000 images the photographers took, more than 20,000 photos were archived, and at least 15,000 have been digitized by the National Archives.

Many of the photos were taken before the US regulated things like water and air pollution.

The Trump administration has already moved toward rolling back a number of environmental regulations, including the Clean Water Rule — which prevents industries from dumping pollutants into waterways and wetlands — and the Clean Power Plan — the Obama administration's biggest initiative to fight climate change by curbing emissions.

Progressives around the country also worry whether Anthony Kennedy's retirement from the Supreme Court will seal the fate of these environmental protections. The 81-year-old justice has been a crucial swing vote on many environmental issues for the past three decades.

On Thursday, Trump announced that EPA administrator Scott Pruitt has resigned, which could make the future of the agency even more unpredictable.

Many reports suggest that if the Trump administration dismantles more of the EPA, parts of the US could return to the state they were in before its regulations.

Take a look at a few New York City Documerica photos that were taken between 1973 and 1974.