Before President Richard Nixon created the Environmental Protection Agency in 1970, water and air pollution weren't federally regulated.

Between 1971 and 1977, the EPA enlisted 100 photographers to document the conditions of the country and the environment with "The Documerica Project."

The result was 81,000 photos, often filled with smoke, smog, acid, oil, rubbish, and sewage. We've selected 35 of those photos to show what American cities used to look like.

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Don't let the soft, sepia tones fool you. The United States used to be dangerously polluted.

Before President Richard Nixon created the Environmental Protection Agency in 1970, the environment and its well-being was not a federal priority.

In the early 1970s, the EPA launched the "The Documerica Project," which leveraged 100 freelance photographers to document what the US looked like. By 1974, there were of 81,000 photos. The National Archives digitized nearly 16,000 and made them available online.

Many of the photos were taken before water and air pollution were fully regulated. The Clean Air Act was passed in 1970, and the Clean Water Act was passed in 1972.

Baltimore, Birmingham, Cleveland, Delaware, Denver, Kansas, Los Angeles, New Orleans, New Jersey, New York, Philadelphia, Pittsburgh, and San Francisco all feature here, in shots filled with smoke, smog, acid, oil, rubbish, and sewage.

None of the 35 photos are pretty (other than the film-photo haze), but it's worth remembering what US cities used to be like before we cared what we put into the air, soil, and water.