The National Park Service has banned drones from flying over the Appalachian Trail. Parks were directed in June to take steps to prohibit the use of the increasingly popular aircraft, which are often used to take photos and videos. The Park Service says drones could affect resources and visitors in ways it has not considered. The ban takes effect immediately and lasts until the Park Service can develop an appropriate policy. The Appalachian Trail, which stretches from Maine to Georgia, is the longest marked trail in the country.