The environmental movement in various forms can be traced far back in American history. Henry David Thoreau described his environment and was sensitive to its value. Theodore Roosevelt championed the environment when he preserved areas of public land from development.
The modern meaning of "environmentalism," in the sense of a popular movement employing courts as well as legislature to further its agenda, can to a large degree be traced to "Silent Spring," by Rachel Carson, which appeared in 1962.
Radical environmentalism, which accepts the need for violence against corporate interests to protect the environment, is an even more recent development. It shares a certain amount of philosophy with Anarchism.