A campfire burns at the Headwaters Campground at Flagg Ranch located near the southern edge of Yellowstone National Park, Wyo., July 5, 2015. A group of F.E. Warren Air Force Base Outdoor Recreation trip participants stayed at the campground the weekend of July 3 to 6 as part of an outdoor trip exploring Yellowstone and Grand Teton National Park. (U.S. Air Force photo by Lan Kim)