The Espinazo del Diablo, the Devil's Backbone, is a ridge of the Sierra Madre Occidental that the old highway between Durango and Mazatlan followed for decades along its crest, with the ground falling steeply away on both sides, and the narrow road with few barriers seemed to hang between two valleys. At about 2,400 metres, the air is cold and the pine forest thick, and on a misty morning the road disappears into cloud. Truckers called it the most frightening road in Mexico, and the name stuck.
The road has changed. In 2013, a new toll highway, the autopista 40D, opened across the sierra with a series of long tunnels and bridges, including the Baluarte Bridge, a cable-stayed span that is one of the highest in the world, standing about 390 metres above the river. The journey that once took six hours or more is now about half that, and most traffic uses the new road. The old highway remains, and riders who prefer curves to speed can still take it, though it is narrow and sometimes in poor condition.
The country is wild and beautiful. The sierra is covered with pine and oak forest, with deep canyons, waterfalls and small mountain villages, and the air smells of resin. La Ciudad, a lumber town about eighteen kilometres away, sits in the forest, and the logging trucks that rumble through are a reminder of the main industry. Farther west, as the road descends toward the Pacific, the vegetation changes to tropical, with mango trees, banana plants and warm, humid air.
Services are scarce along the high section. La Ciudad has a small supply of fuel and food, but you should not depend on it, and it is wise to fill up in Durango or El Salto before climbing, and carry a little extra if you can. The toll road has fuel stations at intervals. Fog is common, sometimes thick enough to reduce visibility to a few metres, and the road can be icy in winter, so check conditions. Trucks and buses use the old road, and they often take the middle of the bends. The best season is spring or autumn, and the best time of day is mid-morning, when the mist clears.