But national parks exist in the real world, surrounded and often invaded by forces they're designed to resist, from pollution to new roads and commercial resorts. To publicize these threats, the National Parks Conservation Association (NPCA) produces an annual list of endangered parks—a distressing roster that this year extends to every corner of the country, from the Alaskan Arctic to the Florida Everglades.

The complete list of endangered parks Alaskan parks Big Bend New York's Fire Island National Seashore Frederick Douglass National Historic Site in Washington, D.C. Glacier Petrified Forest Great Smoky Mountains National Park in North Carolina and Tennessee Tennessee's Stones River National Battlefield Florida's Everglades, Big Cypress, and Biscayne Bay Yellowstone For information: (800) 628-7275 or www.npca.org.

Half of the most threatened parks are located in the West. The most emblematic may be America's original national park, Wyoming's Yellowstone, which has been overrun by snowmobiles—a problem that also plagues Alaska's parks. Alaska—with Denali, Katmai, and other large parks—contains roughly two-thirds of the National Park Service's 83 million acres. A prodevelopment Congressional delegation and presidential administration have put Alaska's parks collectively on this year's list.

At the other end of the country, Big Bend on the Texas-Mexico border— the most important example of protected Chihuahuan desert in the United States—is threatened by air pollution and reduced Rio Grande flows, while encroaching development along park boundaries is a problem for both Arizona's Petrified Forest and Montana's Glacier. The NPCA defines itself as "a citizen-run watchdog" of the National Park Service, dedicated to the preservation and enhancement of our 384 national repositories of natural and human history. The 450,000-member organization got its start in 1919, evidence that even then our institutionally exalted places were far from invulnerable.

The NPCA's chief concern about the current presidential administration is its commitment to robust federal funding. Although George W. Bush promised to spend $5 billion over the next five years to tackle Park Service problems, his 2002 budget allotted a mere $439 million to the parks—and that was earmarked mostly for building and road repair, not the protection of natural resources.