[In the National Park Service] there were clear parallels with the struggle for survival in the natural world. . . . The struggle was not as violent and predatory as in the animal world. It was . . . more like the competition among plants. Certain branches and divisions had a favorable place in the sun. They overshadowed the others and got the major share of the funds, as well as major representation on policymaking and planning committees.—LOWELL SUMNER, 1968

Yellowstone was not created to preserve an "ecosystem."—HORACE M. ALBRIGHT to GEORGE B. HARTZOG, JR., July 1972

Much of the history of the National Park Service from the George Wright era on involved a conflict not between "good" intentions and "bad" intentions, but between two idealistic factions—each well-meaning but committed to different perceptions of the basic purpose of the national parks. One group, by far the stronger and exemplified by Conrad Wirth's career, emphasized recreational tourism and public enjoyment of majestic landscapes, along with preservation of a semblance of wild America. Wirth's understanding of the mandate to leave the parks "unimpaired" was tied to preservation of park scenery. The other group, represented mainly by the wildlife biologists, whose influence had diminished substantially since the 1930s, focused on preserving ecological integrity in the parks, while permitting development for public use in carefully selected areas. In effect, this group defined "unimpaired" in biological and ecological terms—a concept more compatible with that expressed in the 1964 Wilderness Act.

The conflict between these two factions intensified during the environmental era, when park science and ecology received a strong boost from outside the Service, forcing the bureau's tradition-bound leadership to reconsider its policies and make organizational adjustments. Reflecting ecological concerns, the 1963 reports of the Leopold Committee and the National Academy of Sciences on biological management and science in the parks appeared as Mission 66 was approaching its vigorous conclusion, the apex of a half-century of recreational tourism management. During the 1960s, programs tied to tourism in the national parks would proliferate. As had happened in the 1930s, the ongoing development and the new endeavors that the bureau launched monopolized the attention of the Park Service, in part because they represented a continuation of traditional interests with which the Service felt competent and at ease. Within this context of exceptional recreational tourism activity, the reemerging science programs would seek to thrive.