Photograph of Roy Ozmer (1889-1969) and Arthur Woody, chief ranger of the US Forest Service, circa 1930s. Ozmer is standing on the right in this image.

Howard Zahniser (1906-1964) was a long-time leader of the Wilderness Society and was the author of the original draft of the Wilderness Act of 1964, which now preserves more than 100 million acres of wilderness in the United States.

Marking the Appalachian Trail in the Great Smoky Mountains National Park. Albert Roth is adding one of the original AT blaze signs to the trail route just south of Clingman's Dome.

Myron Avery during a survey of the route of the Appalachian Trail in the Great Smoky Mountains National Park.

Myron Avery and two other hikers on the summit of Mount Katahdin (Maine).

Myron Avery on Hawksbill Mountain in Shenandoah National Park with his famous measuring wheel. Avery was rarely without his wheel when he was on the trail.

Myron Avery points out a trail location in the late 1930s. Pictured with Avery (pointing with an axe) are, from left, PATC members Howard Olmstead, Bob Beach, Dr. Laurence Schmeckebeier, and Mary Jo Williams.

Photograph of Benton MacKaye and Myron Avery at Bake Oven Knob, October 1931. This is the only known photograph of the two men together.

Benton MacKaye, who was first to propose the Appalachian Trail, poses for a photo along the Trail near Newfound Gap in the Great Smoky Mountains National Park on September 24, 1933.

Still image of Benton MacKaye