In 1971, the United States Environmental Protection Agency announced its DOCUMERICA project, an ambitious endeavor intended to photographically observe Americans, their surroundings, and their daily impact on the environment.
With former National Geographic photo editor Gifford Hampshire at the helm, the project began in earnest in January of 1972, providing freelance photographers a per diem allowance and an unlimited supply of film.
By 1978, when the initiative was dissolved, these shooters had produced more than 20,000 images, nearly 16,000 of which have been digitized by the United States National Archives and can be viewed on their website. The Archives has also published many of these images, sorted by their respective photographers, on Flickr.
The EPA has also created a small collection on Flickr titled DOCUMERICA: Then and Now, which includes side-by-side comparisons of the original images with new ones taken in the last few years, noting the hits and misses of environmental awareness in the past 40 years. (The naturally-occurring color fades on the before images make the images look grimier than they really are, but the differences are still evident.)