GATLINBURG, Tenn. – Each year thousands of people hike all or part of the 2,175-mile-long Appalachian Trail from Maine to Georgia.

And for each cleared footpath, clean toilet or comfortable shelter, the hikers should thank the network of volunteers who help maintain the trail.

The AT is technically a national park, but volunteers organized through the Appalachian Trail Conservancy and hiking clubs keep it open.

A small exhibit at the Great Smoky Mountains National Park, which contains 71 of the most-traveled miles on the AT, is hoping to educate visitors about the importance of volunteers.

“I think it’s one of the neatest things about this trail,” hiker and author Cindy Ross said. “Even though it’s a government organization that’s in charge of it, if it wasn’t for the volunteers there wouldn’t be a trail.”

A forester in New England named Benton MacKaye is credited with the idea for the Appalachian Trail in 1921.

The Appalachian Trail Conference, later called the Appalachian Trail Conservancy, was founded four years later to organize the clearing of the trail, mostly by volunteers. It was completed in 1937 and crosses six national parks and eight national forests.

The AT became a national scenic trail in 1968 by an act of Congress. The National Park Service delegated management to the ATC and provides some of the group’s funding. Hiking clubs along the trail help organize volunteers.

The ATC estimates about 4 million people step foot on the AT a year. Between 2,000 and 3,000 start with the intention of hiking the entire trail; of those, between 600 and 1,200 finish.

About 11,400 people spent the night along the Appalachian Trail in the Smokies last year, according to backcountry permits and reservations issued by the park.

Ross hiked the entire AT in 1978-79 after having to stop in the middle to recover from a broken foot. Her book, “A Woman’s Journey,” chronicles the experience. She spoke about it in a lecture series last month in conjunction with the exhibit.

“We wanted to bring out this idea that everybody can walk a part of the AT. You can get out of your car at Newfound Gap and walk either direction, north or south, as much as you want,” said Phyllis Henry, a volunteer coordinator with Smoky Mountains Hiking Club. “Anybody can experience the AT no matter what age.”

Henry helped put together the AT exhibit at the Sugarlands Visitor Center near the Gatlinburg entrance to the park. It is scheduled to remain open through October.

The exhibit, while covering only two walls in a corner, displays a pair of worn-out boots used by a “thru-hiker,” the term for someone who hikes the entire trail. It also notes that it would take 5 million steps to walk the whole trail.

A similar exhibit is located in the Shenandoah National Park in Virginia, and visitors can search the archives or see a giant relief map of the trail at the ATC headquarters in Harpers Ferry, W.Va.

The Smokies exhibit includes a portion on volunteers with pictures.

“I just don’t think a lot of folks know it’s maintained by volunteers. They have this misconception that the park service takes care of it,” Henry said.

Last year more than 5,500 people volunteered some 195,000 hours on the trail. In the Smokies, trail “maintainers” pitched in 11,000 hours.

The AT gets a big push on National Trails Day, which is today, when volunteers work all day on certain sections.

“Even with all that help there’s still lots more to do,” said Morgan Sommerville, ATC’s regional director in Asheville, N.C.

“There’s a lot of backlog of work to be done. We’re working as quick as we can to do it. Almost all of the work is done by volunteers so we have many years of work left to do to bring the Appalachian Trail in the Smokies up to a reasonable standard.”

The trail portion in the Smokies is plagued mainly by erosion caused by heavy rainfall and a steep terrain – Clingmans Dome on the Tennessee-North Carolina line is the AT’s highest point at 6,643 feet.

Volunteers, either working one day a year or for days or weeks at a time as part of a crew, install and clean water bars, which are used to keep water off the trail. They trim overgrowth, clear fallen trees, pick up trash and help build bridges or steps.

Remote sections are even harder to maintain because they may require volunteers to spend all day hiking there. Sometimes material has to be flown in by helicopter.

And somebody has to tend to the backcountry toilets and keep them stocked with mulch to compost the waste.

“It’s not as unpleasant as it sounds,” Sommerville said, “but it’s something we’re always seeking volunteers for.”

On the Net: ATC: www.appalachiantrail.org.