The Wilderness Act of 1964 began as an idea first floated at the Sierra Club's Second Wilderness Conference in March 1951. Wilderness Society member Howard Zahniser proposed that members of the Sierra Club, the Wilderness Society, and other conservation groups, begin a campaign for legislative action to preserve the wild places in America's public lands from the encroachment of roads such as Skyline Drive in Shenandoah National Park and the Blue Ridge Parkway further south.

Zahniser's proposal was a direct outgrowth of Benton MacKaye's struggles with Myron Avery over the future of the Appalachian Trail in 1935. At the time, MacKaye had fought hard for the preservation of the wilderness character of the Trail's route through the mountains of the East, while Avery had insisted that completing the Trail from end to end was the most important objective, even if that meant compromising the National Park Service over the issue of roads in wilderness areas. 

Howard Zahniser

The legislative campaign first proposed by Zahniser in 1951 grew in strength over the coming decade, and eventually culminated in 1964 the Wilderness Act, which Zahniser wrote, passed the Congress and was signed into law by President Johnson. At the signing ceremony for the Act, President Johnson said:

If future generations are to remember us with gratitude rather than contempt, we must leave them something more than the miracles of technology. We must leave them a glimpse of the world as it was in the beginning, not just after we got through with it.

Most of the lands covered by the Wilderness Act were located in the Western U.S., and so the Appalachian Trail was initially little effected by the new law. And in any case, most of the Trail passed through lands that were hardly wilderness. Even in the National Parks and National Forests, the Appalachian Mountains had been extensively farmed, logged, and mined for decades, even centuries, and so the preservation of "wilderness" took on a different meaning along the A.T. corridor than it did in the West. The larger impact of federal wilderness protection in the East began with the passage of the Eastern Wilderness Act of 1975, which extended the same protections afforded in the earlier act to federal lands in the East, eventually including significant portions of the Trail in designated wilderness areas.