tions is a powerful one, yet the language of some of the early national parks legislation was not adequate to ensure full realization of that concept. The Yellowstone Park Act of 1872, which created the world's first national park, calls for a "public park or pleasuring-ground" (30 U.S.C.A. §21), and its enactment ushered a revolutionary idea into human thought and values. But over time it became clear that the Yellowstone legislation and other acts that created park sites did not accomplish the whole job of protecting natural and cultural resources. To enhance the legislative mandate, in 1900 Congress passed the Lacey Act (16 U.S.C.A. §§701, 3371–78, and 18 U.S.C.A. §42) to protect wildlife and natural features, and in 1906 it passed the Antiquities Act (16 U.S.C.A. §§431–33) to allow for the reservation of federal lands as national monuments and to halt commercial exploitation of cultural and historic objects taken from the public lands (Coggins and Wilkinson, 1987).
But it is the National Park Service Act of 1916 (the Organic Act), still in effect today, that provides basic statutory authority for the NPS, declaring the agency's mission to be
[T]o conserve the scenery and the natural and historic objects and the wild life therein and to provide for the enjoyment of the same in such manner and by such means as will leave them unimpaired for the enjoyment of future generations (16 U.S.C.A. §1).
In this simple language, the Organic Act united the well being of the American spirit, perhaps indeed the human spirit, with the survival of the nation's aesthetic, natural, and cultural heritage. At the time it might have seemed that the resources would survive in the newly protected areas without much additional help from humankind, but we now know that accomplishing the agency's mission in the face of myriad growing and complex threats requires sophisticated understanding of park resources, the forces of change that affect them, and the measures needed to protect them.
The NPS's original management strategy generally assumed that its mission could be achieved through passive management, simply by keeping direct human encroachment to a minimum and by maintaining the "natural" status quo for recreational enjoyment. The 1916 mandate emphasized