They don't have to be.

By Douglas Gantenbein
Updated: February 02, 2017

America's national park system is regarded as one of this country's great ideas. The parks did not always exist, of course: they were created, beginning in 1872, specifically to preserve our natural and cultural heritage. It was a radical concept, setting aside millions of acres of supremely valuable land to preserve those places that generations of Americans have believed were most worth protecting. Other countries have tried to emulate this effort; none has succeeded so well. Today, the National Park Service oversees 388 parks, monuments, and recreation areas. Many of them are in trouble, with pollution, budget cuts, and unchecked development combining to damage them. And in a presidential election year, they've also become a political football, with the Bush administration and its critics squaring off over what needs to be done—and who is to blame.

How bad are things?"We've reached a crisis point over the past three years," says Thomas Kiernan, president of the National Parks Conservation Association, a watchdog group that monitors the parks. Kiernan sees three key threats to America's parks:

• Annual budget shortfalls that have left the system with insufficient funds to handle chronic maintenance headaches (shoddy roads, buildings in disrepair, inadequate water and sewer systems) and keep staffing at necessary levels. Most observers say another $600 million each year is required to keep pace with crumbling infrastructure alone.

• Air pollution, which in parks such as Virginia's Shenandoah rivals that of metropolitan areas.

• Outside threats, including encroaching real estate development, new coal-fired generating plants that will create more pollution, and road construction that could block wildlife migration into and out of parkland.

In many locations, visitors can easily feel the impact of these problems. At parks such as Grand Canyon the odds are low that a traveler will ever meet a ranger—not to mention get a fast response in an emergency. At Chaco Culture National Historical Park in New Mexico, ancient stone structures are visibly decaying. Venture up the peaks of Great Smoky Mountains National Park, and the ozone might make your lungs burn.

Although the park system has been cash-starved for years, the Bush administration has opened itself to criticism in large part because of George W. Bush's pledge, during the 2000 campaign, to "restore and renew" the parks. Critics of the administration note that under Bush's watch, the Department of the Interior, which manages the park system, has given away water rights to the Colorado River at the expense of the Curecanti National Recreation Area; lobbied to allow exhaust-belching snowmobiles in Yellowstone National Park; and cut back staff under the euphemism "service level adjustments." The park service director, Fran Mainella, responds by touting the system's highest-ever budget, $2.4 billion, but that figure is 20 percent lower than it was 25 years ago when adjusted for inflation. And during those decades the system has added 50 sites, while visitation has increased by 60 million people.

Not all the news is grim. Yosemite Valley is still an awe-inspiring cathedral of salt-and-pepper granite, the USS Arizona Memorial at Pearl Harbor a place where you can ponder the shock of that December day, the Virgin Islands National Park home to schools of startlingly bright parrot fish. So go see the parks now—there's never been a better time to remind ourselves that they are fragile things, worthy of protection.

DOUGLAS GANTENBEIN, a Washington State-based journalist, is the author of A Season of Fire (J. P. Tarcher).

Not all the national parks are equally threatened. Here is a representative sample, including both important success stories and places at risk.

1. Wrangell-St. Elias National Park
The largest of the parks, glacier-studded Wrangell-St. Elias is also one of the most spectacular. Its remote location keeps visitor impact low, but increasing use of all-terrain vehicles is harming trails and streams.

2. Olympic National Park
Mountainous Olympic is struggling with budget problems that have forced it to trim backcountry staff and reduce operations at visitors' centers. On the plus side, the park is going ahead with plans to remove two aging dams on the Elwha River, a prime salmon-spawning stream.

3. John Day Fossil Beds National Monument
One of the system's hidden gems, John Day is quiet (just 100,000 visitors a year) and combines a stunning landscape (water-cut canyons of turquoise stone) with a storied past (giant rhinoceroses once roamed the area). New this year is an $8 million paleontology center.

4. Sequoia National Park
Sequoia is a vast area of mountains, rivers, and the towering trees that are its signature feature. Air quality is among the worst in the park system, however, and armed marijuana growers have staked out its remote corners.

5. Death Valley National Park
Overcrowding is a problem in many parks, but not here, where 1 million visitors annually all but disappear in its 3.4 million acres. The park is in terrific shape, although budget cuts have reduced staff and maintenance.

6. Arches National Park
Seen in Thelma and Louise, Arches is known for its 2,000-plus sandstone arches and terra-cotta-red soil. In the past decade, nearby Moab has become a capital of extreme sports, leaving the park packed with cars on spring days.

7. Yellowstone National Park
The granddaddy of U.S. parks, Yellowstone is magical, with its steaming geysers, bison herds, and panoramic views. Maintaining historic structures and keeping pace with visitor demands, however, could cost $22 million a year more than the park is able to spend. Snowmobile use will also likely be returning this winter.

8. Glacier National Park
One of the park system's jewels, Glacier is beautiful: 1 million acres of peaks, valleys, forests and, of course, glaciers. But climate change means those glaciers are disappearing fast; Grinnell has shrunk more than 60 percent since record-keeping began. Some fear they could vanish altogether by 2030. Forest fires have plagued the park in recent years, too.

9. Little Bighorn Battlefield National Monument
Political differences between Custer aficionados and Native Americans make this park difficult to run, but managers get good marks for maintaining it well with limited funds. New last year was a memorial to Native Americans who died in the battle.

10. Badlands National Park
A trove of fossils from 33 million years ago, Badlands today is an eerie landscape of prairie abutting deeply carved cliffs and pinnacles. Chronic budget problems mean park staff can't keep up with new fossil finds, and visitors' center hours have been reduced.

11. Voyageurs National Park
A pristine park of lakes surrounded by granite cliffs and pine forests, Voyageurs is beloved for canoeing and fishing in summer, cross-country skiing and snowshoeing in winter. Global warming now threatens to dry lakes and change the mix of tree and animal species.

12. Big Bend National Park
Big Bend, a sprawling area of rivers, mountains, and desert, is affected by air pollution from both the U.S. and Mexican sides of the border. Water demands on the Rio Grande are so severe that last year the river went dry within the park.

13. Big Thicket National Preserve
Big Thicket, which encompasses both desert and tropical ecosystems, is among the most endangered of the parks. It is split into many small parts, and development threatens to overwhelm them. Oil and gas exploration could also harm the delicate landscape.

14. Shiloh National Military Park
A Civil War battlefield that looks much as it did on the eve of the fight there, Shiloh gets a new$9 million interpretive center this summer. And the park is purchasing adjacent land to protect it from development.

15. Biscayne National Park
One of the country's largest marine parks—a paradise for boaters, fishers, and divers—is plagued by overfishing, damage to coral reefs, and too many powerboats. Park managers are attempting to restrict boat use in some areas, but opposition is proving fierce.

16. Congaree National Park
The newest full-fledged park, Congaree is a river floodplain of moss-draped hardwood trees. With visitor levels surging, the park is scrambling to take care of basic needs, though ranger Fran Rametta still has time to chat with the curious.

17. Mammoth Cave National Park
Most visitors forgo spelunking to hike its forests and paddle its rivers. Air pollution can be terrible in summer, however—and things may get worse if a planned coal-fired power plant is built 50 miles away.

18. Fredericksburg and Spotsylvania National Military Park
This park is home to some of the pivotal battlegrounds of the Civil War. Preservationists have helped defeat a 2,000-home subdivision and a freeway to be built nearby, but another large subdivision next to one site is still being developed.

19. National Underground Railroad Network to Freedom
The network is not one site, but a collection of houses, museums, and other buildings associated with the spiriting of slaves to freedom. It is drastically underfundedand can't even train staffers, let alone alert the public to its existence.

20. Acadia National Park
Everyone loves the park's accessible trails, water views, and miles of gravel-paved "carriage roads." Yet Acadia is too well-loved in August, when the bulk of the 2.5 million people who visit each year arrive. And chronic pollution from New York and other nearby states often renders the air unclean.