Gene Espy's scrapbook (page 18 of 40) from his thru hike in 1951. This page shows views of Center Point Knob, PA, which was the halfway point of the trail in 1951.

On August 6, 1951, Northbound (NOBO) thru hiker Gene Espy met Southbound (SOBO) thru hiker Chester Dziengielewski at the Smith Gap Shelter in Pennsylvania. This grainy photograph is the first ever image of a meeting between a successful northbound and successful southbound AT thru hiker. It is also the only known photograph on the trail of Dziengielewski, the third person to thru hike the AT.

In 1951, four hikers traversed all or almost all of the Appalachian Trail from end to end in one season. Three of those hikers, Gene Espy, Chester Dziengielewski, and Martin Papendick, hiked the entire trail, making them the second, third, and fourth thru hikers after Earl Shaffer in 1948. Bill Hall completed all but 300 miles of the trail, skipping the route between Roanoke and Damascus to save time and money. Pictured here, from left to right, are Dziengielewski, AT founder Benton MacKaye, Bill Hall and Gene Espy. The photograph was taken in October 1952, at a dinner hosted by the Georgia Appalachian Trail Club to honor the three hikers who attended. Papendick was thru hiking the Pacific Crest Trail at the time.

Marine Corps Veteran and 2012 thru-hiker who went on to found Warrior Expeditions.

Thru hiker "Taxman" somewhere in the Mid-Atlantic during the summer of 1983.

Hikers "Linus" and "Woodstock" on the Appalachian Trail near Pennsylvania Highway 16, May 11, 2000.

"Chewy" at the Virginia/Tennessee border, just south of Damascus, Virginia.

Thru hiker Julius Bruggeman passing through Shenandoah National Park, June 12, 1970. Unlike most Appalachian Trail hikers, Bruggeman made his own pack and much of his other gear.

A group of women who called themselves the "Mountain Marchin' Mamas" backpacking on the Appalachian Trail in the spring of 1988.

A group of backpackers on the Chimney Pond Trail, near Mount Katahdin in Maine, July 1, 1939.

A member of the Philadelphia Hiking Club resting along the Appalachian Trail near Smith Gap, April 19, 1935.

Members of the Philadelphia Trail Club at an unidentified Appalachian Trail shelter, Easter Weekend, 1933. At the far right is Mary Kilpatrick, the first woman to hike every step of the Trail and a long-time leader of the Philadelphia Trail Club.

The man on the left is George W. Outerbridge, the second person to hike every step of the Appalachian Trail after Myron Avery. He is standing next to Mary's husband, Martin Kilpatrick, and, like Mary, a leader of the Philadelphia Trail Club.