The Wilderness Act of 1964 established the National Wilderness Preservation System, an area of land that now encompasses over 95 million acres (38.5 million ha). According to the law, wilderness is "an area where the Earth and its community of life are untrammeled by man, where man himself is a visitor who does not remain...land retaining its primeval character and influence, without permanent improvements or human habitation, which is protected and managed so as to preserve its natural conditions." This law represents the core idea of preservation: the need to preserve large amounts of land in its natural condition. This idea, which arose in the late 1800s, is in stark contrast to the desire to control nature and exploit the resources of nature for economic gain.

The early preservation movement focused on protecting natural areas through their designation as national parks. The birth of the wilderness system, however...