There is no specific moment marking an actual beginning to America's awareness of the delicate balance between nature and society, but there is also no doubt that the environmental movement came to national importance in the 1970s. That was when the general population became conscious of two intertwined ideas: human dependence on nonrenewable resources, and the environment's inability to absorb the pollutants that were discarded into it.

Environmental awareness had appeared in intellectual works throughout the country's history, most notably in the writings of Henry David Thoreau, whose 1845 book Walden documented his attempt to live naturally in the woods, simplifying his life by freeing himself of the trappings of society. In the following century, small movements sprung up, mostly over local causes, protesting specific abuses of the environment. The world's first protected National Park, Yellowstone, was set aside by Congressional fiat in 1972; the Audubon Society, a collection...