In Secretary Lane's third annual report in 1919 the National Park Service policy was announced under three broad principles:
First, that the National Parks must be maintained in absolutely unimpaired form for the use of future generations as well as those of our own time; Second, that they are set apart for the use, observation, health, and pleasure of the people; and Third, that the national interest must dictate all decisions affecting public or private enterprise in the Parks.[339]
Since then the program has made steady progress. Its purposes and policies have been enlarged and clarified. The acceptable qualities of parkhood were defined. Such an area must be supremely significant, having a national appeal whether scenic, archaeological, scientific, or historical. Only such features of natural architecture were to be included as would represent the highest accomplishment within its class. For example, Grand Canyon of the Colorado exemplifies the most extraordinary achievement of stream erosion, whereas Yellowstone is most unique in the realm of thermal activity.[340]
The National Park represents the apex of the conservation program, wherein the principle of optimum use is the dominating force. The twin purposes of enjoyment plus conservation always remain uppermost. Commercialization beyond actual requirements is not to be tolerated, and to this end close supervision is maintained.
Natural species of animals and plants were to abide in normal relationships, free from man's interference, except under urgent circumstances such as were described in the discussion of wild life control. The primitive appearance of Yellowstone forests is distasteful to some people. It was a carping German traveler who said, "Look at your dead trees and burned stumps in the woods ... and your streams are full of driftwood. It is not cared for."[341] In that sense Yellowstone is not a park but a wilderness full of the beauty of natural disorder. All things remain as nature leaves them. No man disturbs landslide, log jam, or wind-swept lodgepole avalanche.
The appearance of the trails, roads, bridges, buildings, and facilities of all kinds is gradually being brought into harmony with the natural environment. Under the guidance of landscape artists, structural design and location are made conformable to maximum scenic advantages while at the same time, being inconspicuous themselves. A few examples will illustrate this trend toward artificial recession. In 1889 Captain Boutelle complained against the statute which prescribed that no hotel shall be erected within four hundred and forty yards of any object of interest. He urged a reduction of one-half the distance.[342] Now, all the accommodations in the immediate Grand Canyon area are being moved a modest distance away, where they will still provide the services which visitors need, but not intrude upon the natural scene. Another case is afforded by the bear shows. Formerly they were provided in several places; then modified to a less artificial presentation on Otter Creek. In 1942 they were discontinued. It is truly exciting for thousands of people to observe thirty or forty grizzlies jostle and cuff each other around a "combination salad" platform. Still, the circumstance is highly artificial, a sort of Roman holiday affair, and therefore inappropriate. It is hoped that the Lord of all American wild life may be allowed to go his way undisturbed, otherwise grizzlies may become "holdup bears and bums." Such an eventuality, on a nocturnal basis of operation, is by no means improbable. That development would consign this magnificent animal to a precipitous disappearance from the earth.