Guides (ahead and behind) lead visitors on a mule ride down Bright Angel Trail into the gorge at Grand Canyon National Park in northern Arizona.
The ride, at times steep, is reported by those who have taken it to be dramatic (and to some a bit traumatic) heading along an edge into the abyss on the way down and less harrowing coming back up, when the riders and animals hug a safe rock wall. Original image from Carol M. Highsmith’s America, Library of Congress collection. Digitally enhanced by rawpixel.