The Appalachian Trail Conservancy (ATC) is a nonprofit organization dedicated to the conservation of the Appalachian Trail, a route in the eastern United States that runs from Maine to Georgia. Founded in 1925, the ATC is responsible for the day-to-day management of the Appalachian Trail under a cooperative agreement executed with the National Park Service. It is the lead non-governmental organization in protecting the trail's 2,193 miles (3,529 km), 250,000-acre (1,000 km²) greenway and coordinates the work of some thirty-one Appalachian Trail maintenance clubs, performing almost all of the on-the-ground maintenance work. The National Trails System Act, which established the National Trails System and brought the Appalachian Trail into the federal estate, enabled the trail to be managed as it had been since 1925, with central agency and NGO (ATC) coordination, but most trail work being performed by, in 2019, almost 6,000 volunteers.

The Appalachian Trail, also called the A.T., is a hiking trail in the Eastern United States, extending almost 2,200 miles (3,540 km) between Springer Mountain in Georgia and Mount Katahdin in Maine, and passing through 14 states. The Appalachian Trail Conservancy claims the Appalachian Trail to be the longest hiking-only trail in the world. More than three million people hike segments of the trail each year.