ABSTRACT
The Sierra Madre Occidental presents one of the most formidable obstacles to land transportation in Mexico. Throughout its length of 750 miles, from a point near the United States-Mexico boundary in the north to the Santiago River in the south, no railroad, auto road, or cart trail has ever traversed this barrier. The routes for wheeled vehicles between the west coast and the interior plateau have avoided the Sierra Madre. The most important of the rounds the southern end of the Sierra, using the pass traversed by the Southern Pacific Railroad through the barranca country of eastern Nayarit and western Jalisco to Guadalajara. The establishment and maintenance of the Topia Road in the last quarter of the sixteenth century were closely associated with the search for, and exploitation of, precious metals in the Sierra Madre. Exploitation of the rich silver deposits around Topia probably did not begin until the 1580s.
