Mexico is studded with mountain ranges, the two largest being the Sierra Madre Occidental range and the Sierra Madre Oriental range. These ranges run roughly parallel to one another for most of their courses, although they eventually merge south of Mexico City. The Sierra Madre Occidental range sits to the west, extending from the Arizona border southeastward. The Sierra Madre Oriental lies farther east, rising near the Texas border and also running southeastward. To the south of the Sierra Madre Occidental, the Sierra Madre del Sur range runs along Mexico's southern Pacific shoreline. The mountains of the Sierra Madre del Sur slope magnificently into the sea; this scenic resort area is sometimes referred to as the Mexican Riviera. Farther south still, near the Guatemalan border, Chiapas Highlands are covered in lush tropical jungles. Lastly, coastal ranges extend throughout the length of the narrow 750-mile-long Baja Peninsula west of the Mexican mainland.
The Central Plateau, also called the Mexican Plateau, sits between the Sierra Madre Occidental range and the Sierra Madre Oriental range, extending from the border with Texas and New Mexico southward until these two mountain ranges merge. The plateau slopes gently upward from north to south, lying at about 3,000 feet near the U.S. border and rising to 8,000 feet at its southern end. Deserts and arid brush lands cover much of the plateau. The southern part of the Mexican Plateau is known as the Valley of Mexico; the nation's capital, Mexico City, lies in this population-dense area.
To the east of the Sierra Madre Oriental range, the coastal plain of the Gulf of Mexico usurps most of Mexico's eastern edge. The northern portion of the plain features numerous lagoons. In the south, the plain widens into the largely flat Yucatan peninsula. The Yucatan divides the Gulf of Mexico from the Caribbean Sea. Much of it is covered with jungles and fertile farmland.
To the south of the Valley of Mexico, over 20 volcanoes rise out of the Earth's crust. Extending roughly in a line across the country from the Pacific to the Gulf of Mexico, this stretch is known as the Trans-Mexico Volcanic Belt. Many of these volcanoes are extremely high and snowcapped; one of them, Volcan Pico de Orizaba, rises to 18,701 feet, making it the highest peak in Mexico and the third-highest in all of North America. Some volcanoes in the belt are dormant, while others are active. Popocatepetl, an active volcano, looms over the densely-populated metropolises of Mexico City and nearby Puebla; it is within sight of over 30 million people.
