Of course parks are not static ecosystems and are subject to natural and not-so-natural disasters that may affect trails. In recent years, wildfires have scorched Yellowstone, floods inundated Yosemite Valley, and record snowfalls buried Lassen. Such natural phenomena inevitably damage trails.

The various trail systems evolved on a park-by-park basis and it’s difficult to speak in generalities about their respective origins. A good deal of Yosemite’s trail system was in place before the early horseless carriages chugged into the park. Newer parks, such as Channel Islands National Park, will be building trails well into the 21st century.

Many national parks were aided greatly by the Depression-era Civilian Conservation Corps of the 1930s. Older parks have hand-built trails that are true gems, highlighted by stonework and bridges that would no doubt be prohibitively expensive to construct today. Today volunteer groups help park staff build and maintain trails.

The trail system in national parklands shares many characteristics in common with pathways overseen by other governmental bodies. Often a hiker will notice no profound differences in pathways when, for example, traveling from a national park into a national forest or into a state or regional park.

While sharing similarities with trails in other jurisdictions, national parkland trails nevertheless have unique qualities, too, that distinguish them from pathways elsewhere. One major difference between national parks and, for example, many state parks, is the amount of land preserved as wilderness. Denali, Gates of the Arctic, Glacier Bay and Wrangell St. Elias National Parks encompass some 21 million acres of designated wilderness in Alaska. A majority of such desert national parks as Death Valley and Joshua Tree are wilderness. Wilderness comprises some 94 percent of Yosemite.

On national park maps you’ll find such wilderness areas delineated as simply “Wilderness.” Unlike the Forest Service, the Bureau of Land Management and other wilderness stewards, the National Park Service does not name its wilderness areas.

Wilderness designation is more than a name for a wild or pristine area. By law, a wilderness is restricted to non-motorized entry—that is to say, equestrian and foot travel. Hikers do not have to share the trails with snowmobiles or mountain bikes in national park wilderness.

Other national park service wilderness regulations are designed to protect resources and ensure visitor safety. Review these wilderness regulations before hitting the trail.

The hikers you meet on a national park trail may be different from the company you keep on trails near home. National parks attract visitors from across the nation and around the world. I’ve hiked with Japanese visitors across Death Valley’s sand dunes, with German visitors in the Olympic rain forest, with New Zealanders in the Rockies, with a French couple to the top of Lassen Peak, with Brazilians in the Everglades. Once I counted ten different languages on a popular nature trail in Muir Woods National Monument. Not surprisingly, the park service has printed selected brochures in French, German, Spanish, Japanese and Chinese.

Because of the park’s attraction to visitors worldwide, the park service uses lots of international symbols on its signage, and the metric system as well. This international orientation explains why the national park service seems to be about the only American institution, outside of scientific and medical circles of course, still promoting the metric system.