Technically, today marks the 75th anniversary of its completion. But the 2,180-mile path stretching across 14 states from Springer Mountain, Ga., to Katahdin, Maine, is never really finished.

It took 15 years for hundreds of volunteers, state and federal partners, trail maintenance clubs and young workers with the New Deal-era Civilian Conservation Corps to build the original path. In the decades since, nearly 99 percent has been relocated or rebuilt, and transferred from private to public ownership.

That means the trail and some 250,000 contiguous acres are better-protected than ever from development and suburban sprawl.

It will always be in the same general area, said Mark Wenger, executive director of the Appalachian Trail Conservancy in Harpers Ferry. But as access to waterways or scenic landscapes along the trail becomes available for purchase, it will continue to shift.

"Will it move a little to the left, a little to the right?'' he said. "Yes, depending on the physical attributes of the area.

"One of the tenets of the trail is to provide that personal experience of sort of being one with nature. You can't necessarily do that if you're walking along a major highway,'' Wenger said. "So it's been relocated to give it some degree of privacy and that sense of the wonder of nature.''

The relocations and reconstruction also make the path itself more sustainable. It was originally routed straight up and down many mountains, exacerbating erosion and making for a difficult hike.

Today's trail features more scenic vistas than the original route, too, including Roan Mountain, Tenn.; the Mount Rogers High Country and Grayson Highlands in Virginia; the Pochuck Creek swamp in New Jersey and Thundering Falls in Vermont.

The idea for the trail was born in a 1921 article in the Journal of the American Institute of Architects. Benton MacKaye proposed an idea that still resonates today -- a path that would let people escape the demands and drudgery of daily life.

As many as 3 million people a year now visit some part of the trail to reconnect with nature and slow down.

Wenger calls it "a very complex trail'' with a wide variety of terrain. Travelers can make their way through the dense forests and remote mountains in the South, to long, rocky ridges in the Mid-Atlantic, to rugged and rocky hiking with the possibility of wintry weather in New England. Although some sections meet the accessibility standards of the Americans with Disabilities Act, there are also rugged sections that require skill and experience to navigate.

About 2,000-3,000 people each summer attempt a "thru-hike,'' or journey along the entire length. Only one in four will succeed. For them, Harpers Ferry is the psychological halfway point, even though the actual location is nearby in southern Pennsylvania.

Outside ATC headquarters in Harpers Ferry, Mississippi native Crystal Stroud, 26, opened boxes of supplies shipped by friends and family -- nail clippers and dog food for her trail buddy, a 3-year-old dachshund named Polly, and wipes, trail mix and a loaf of homemade lemon poppy seed bread for herself. Many rural post offices dot the landscape along the trail, so hikers often ship things to those post offices to pick up as they progress on their journeys.

Stroud is hiking north after graduating from Mississippi State University and is craving adventure.

"I did not want to get chained down to a job,'' she said. "I feel like a bird out of a cage out here. I hike as far as I want to hike. I stop when I want to stop. I get to sleep in if I want to.''

Stroud didn't realize what she was getting into. She thought she'd camp and hike for a few weeks. At best, she figured, she'd be ready to quit after she saw Tennessee's Smoky Mountains.

But she kept walking.

"I can't explain it,'' she said. "Life on the trail is amazing. I feel like a kid again, and I don't ever want to leave.''

The trail is part of the National Park System, managed by the trail conservancy, National Park Service, U.S. Forest Service, 31 local clubs and various state agencies. The Maine Appalachian Trail Club in Carrabassett Valley is planning an anniversary celebration Saturday, while the Mount Rogers Appalachian Trail Club in Damascus, Va., will sponsor a day hike.

"We need to take stock of what the people before us have done,'' Wenger said. "If you think about it, building a national trail is in the same caliber as Yosemite and Yellowstone, the early national parks. It's something other countries didn't do.''

It's also important to think about where the trail is headed, he said, and to ensure it remains available to future generations.

"It is not going to be done in my lifetime,'' Wenger said, "and we'd like to think secretly it will never be done. But it will always be our challenge to finish it.''