Documerica Streets in Cleveland, Ohio are obscured by smoke from heavy industry, July 1973.
A growing number of these plants are shutting down, partly due to the declining costs of renewables. According to one recent Moody's Analytics report, the price of wind power has fallen so rapidly that it could soon replace coal-fired plants in the Midwest.
Meanwhile, the Trump administration has confirmed plans to eliminate the Clean Power Plan, the Obama-era program aimed at helping the United States meet its Paris climate agreement goals by curbing carbon emissions from power plants.
The announcement follows a series of other rollbacks from the Environmental Protection Agency. Under administrator Scott Pruitt, the EPA has reversed a ban on a pesticide that can harm children's brains. It has also moved to repeal the Clean Water Rule, which clarified the Clean Water Act to prohibit industries from dumping pollutants into streams and wetlands.
If Pruitt succeeds with these measures, the US could return to some of the same conditions as we had before air and water quality were regulated.
Soon after the EPA's founding in 1970, the agency dispatched 100 photographers to capture America's environmental problems in a photo project called Documerica. Of the 81,000 images they took, over 20,000 photos were archived, and at least 15,000 have been digitized by the National Archives.
Here's a selection of Documerica photos of Midwestern cities that were taken in the early 1970s.