Copper Canyon is not a single gorge but a network of six canyons, covering 25,000 square miles in the state of Chihuahua. Six rivers carved them, all draining the western slopes of the Sierra Tarahumara before merging into the Rio Fuerte and emptying into the Gulf of California. The canyon walls show the copper-green patina that gives the system its name. At the bottom, where water collects and the climate turns tropical, fig trees and palms grow in humid air. At the rim, above 2,400 meters, pine forests stretch to the horizon and temperatures drop below freezing in winter. A single descent traverses climate zones that would span thousands of kilometers at sea level -- from alpine forest to subtropical jungle in a matter of hours.

The Raramuri, whom outsiders call Tarahumara, have lived in and around these canyons for centuries. Their population is estimated between 35,000 and 70,000 -- no official census exists. Many follow a seasonal pattern, occupying cooler mountain regions in summer and migrating deeper into the canyons when winter cold settles on the high plateaus. Their survival strategy has been deliberate isolation: occupying terrain too rugged and remote for anyone else to want, preserving their culture by staying beyond the reach of roads and commerce. Corn is their most important crop. The community race called rarajipari, in which teams kick a wooden ball along canyon paths, is both sport and social institution. Christopher McDougall's book Born to Run brought international attention to Raramuri running, but the running itself predates the attention by centuries.

The most popular way to experience Copper Canyon is aboard the Chepe, the Ferrocarril Chihuahua al Pacifico, which runs between Chihuahua and Los Mochis on the Gulf of California. The railroad was conceived in the late 19th century, but the Mexican Revolution, funding shortages, and the sheer difficulty of building through this terrain delayed its completion until 1961. The finished line comprises 418 miles of track, 39 bridges, and 86 tunnels. The full trip takes approximately 15 hours and passes through the town of Creel at 2,350 meters altitude, the dramatic viewpoint at Divisadero overlooking the Urique Canyon, and the triple-crossing valley at Temoris where the train traverses the same valley three times, including a mile-long tunnel, to gain elevation. Along the tracks, Raramuri artisans lay out food and crafts for sale.

The canyon ecosystem is under extraordinary pressure. Approximately two percent of the original old-growth forest remains. Logging has driven the imperial woodpecker to extinction and pushed the Mexican wolf to the edge. Mesquite and desert ironwood are cut and exported to the United States for charcoal. Open-pit mining for copper and gold pollutes waterways and has been linked to the decline of the Tarahumara frog. Every river in the system has been dammed, causing freshwater shortages in downstream desert communities. Government herbicide spraying aimed at opium poppy and cannabis cultivation threatens non-target species, including a large saturniid moth whose cocoons the Raramuri use in ceremonies. Conservation laws exist on paper, but enforcement in terrain this remote and rugged has been, as one assessment put it, lax or non-existent.

Visitors often arrive expecting a Mexican version of Arizona's Grand Canyon and discover something fundamentally different. Copper Canyon is not one vast chasm viewed from a single rim but a labyrinth of gorges, each with its own character, its own microclimate, its own communities. Batopilas sits at the canyon bottom, a former silver mining town reachable only by hours of switchbacks. Urique occupies another canyon floor, connected to the rim by rough road. Basaseachic Falls, within the canyon system, is one of Mexico's highest waterfalls. The national park established to protect the area spans the municipalities of Batopilas, Bocoyna, Guachochi, and Urique, but the canyons extend far beyond any park boundary. The Raramuri, who know every trail and every seasonal water source, do not need the park designation to understand what they have. They have been running these canyons long enough to know.