Sierra Madre, Principal mountain system, Mexico. It includes the ranges of the Sierra Madre Occidental (to the west), the Sierra Madre Oriental (to the east), and the Sierra Madre del Sur (to the south)—all running roughly northwest-southeast. The Sierra Madre Occidental extends for about 700 mi (1,100 km) parallel with the Gulf of California and the Pacific Ocean; summits reach elevations above 6,000 ft (1,800 m), with some exceeding 10,000 ft (3,000 m). The Sierra Madre Oriental originates near the Rio Grande to the north and extends roughly parallel with the Gulf of Mexico for about 700 mi; it has an average elevation of about 7,000 ft (2,150 m), but some peaks rise above 10,000 ft (Mount Peña Nevada). The Sierra Madre del Sur stretches through the southern Mexican states of Guerrero and Oaxaca, reaching elevations of about 6,500 ft (2,000 m), with a few peaks above 10,000 ft.
