It isn't possible to wrap a national park as if it were a compact disk. Developments outside a park's boundaries can affect it, and what happens inside can be felt far beyond its borders.
That is why a United Nations conservation committee voted in December to designate Yellowstone National Park a World Heritage Site in Danger, citing plans to dig a big gold mine just outside the park.
Indeed, economic growth in the greater Yellowstone region -- an area much bigger than the park itself, which is sometimes called the largest nearly intact natural ecosystem in the temperate zone -- is "one of the greatest long-term threats to the ecological integrity of Yellowstone National Park," said Michael Finley, the park superintendent.
The populations of some communities are growing at the rate of 4 percent a year, he said, and if nearby counties in Idaho, Wyoming and Montana that surround the park were taken together as a single state, it would be one of the fastest growing in the country.
The biggest dispute over growth at the moment involves plans by Noranda Minerals Inc. to build a huge gold-mining operation in the Gallatin National Forest in Montana, just outside the Yellowstone boundary.
Environmentalists warn that the mine's tailings impoundment, where acidic waste rock would be stored, would threaten streams that flow into the park and wetlands that provide important habitat nearby.
Impact under study
An environmental impact statement is being drafted, and the Clinton administration has been putting up other barriers to the development.
The mine's opponents are worried about more than water pollution, which they say could be especially serious if a catastrophic earthquake were to shake the area, where hot springs and geysers testify to the inherently unstable terrain.
Phil Hocker, president of the Mineral Policy Center, an environmental group that focuses on mining issues, said that if the mine were built, the road east of the park from Cooke City, Mont., to Cody, Wyo., would be plowed all winter. That will inevitably increase traffic through the park on the section of road from Cooke City west to Gardiner, Mont., he said, and that will mean more winter visitors -- and stresses.