Crisis in our national parks: how tourists are loving nature to death

As thrill seekers and Instagrammers swarm public lands, reporting from eight sites across America shows the scale of the threat

Just before sunset near Page, Arizona, a parade of humanity marched up the sandy, half-mile trail toward Horseshoe Bend. They had come from all over the world. Some carried boxes of McDonald's Chicken McNuggets, others cradled chihuahuas and a few men hid engagement rings in their pockets. But just about everyone had one thing at the ready: a cellphone to snap a picture.

Horseshoe Bend is one of the American west's most celebrated overlooks. From a sheer sandstone precipice just a few miles outside Grand Canyon national park, visitors get a bird's-eye view of the emerald Colorado river as it makes a U-turn 800ft below. Hundreds of miles from any large city, and nestled in the heart of south-west canyon country, Horseshoe Bend was once as lonely as it was beautiful.