Mexico

I

Introduction

Mexico, in full United Mexican States (in Spanish, Estados Unidos Mexicanos), federal republic in North America, bordered on the north by the United States; on the east by the United States, the Gulf of Mexico, and the Caribbean Sea; on the south by Belize and Guatemala; and on the west by the Pacific Ocean. Mexican federal jurisdiction extends, in addition to Mexico proper, over a number of offshore islands. The area of the country is 1,964,382 sq km (758,452 sq mi). The capital and largest city is Mexico City.

II

Land and Resources

Most of Mexico is an immense, elevated plateau, flanked by mountain ranges that fall sharply off to narrow coastal plains in the west and east. The two mountain chains, the Sierra Madre Occidental to the west and the Sierra Madre Oriental in the east, meet in a region called La Junta in the south-east. At La Junta the two ranges form the Sierra Madre del Sur, a maze of volcanic mountains containing the highest peaks in Mexico (see Sierra Madre). The Sierra Madre del Sur leads into the Isthmus of Tehuantepec, which lies between the Bay of Campeche and the Gulf of Tehuantepec.

The prominent topographical feature of the country is the central plateau, a continuation of the plains of the south-western United States. Comprising more than half the total area of Mexico, the plateau slopes downwards from the west to the east and from the south, where the elevation varies from about 1,830 to 2,440 m (6,000 to 8,000 ft) above sea level, to the north with an elevation of about 1,070 to 1,220 m (3,500 to 4,000 ft). Two large valleys form notable depressions in the plateau: the Bolsón de Mapimí in the north and the Valley of Mexico, or Anáhuac, in central Mexico.

The coastal plains are generally low, flat, and sandy, although the Pacific coast is occasionally broken by mountain spurs. Baja California, a long, narrow peninsula extending about 1,225 km (760 mi) south from the north-western corner of the country, is traversed by mountains that are a continuation of the coastal ranges in the US state of California. The Yucatán Peninsula, which forms the south-eastern tip of the country, is low and flat, averaging about 30 m (100 ft) in elevation.

A

Rivers and Lakes

Mexico has few major rivers, and most are not navigable. The longest river is the Rio Grande (called the Río Bravo del Norte in Mexico), which extends along the Mexican-US border. Other important rivers include the Balsas Pánuco, Grijalva, and Usumacinta in the south and the Conchos in the north. Mexico has few good harbours. Tampico, Veracruz Llave, and Coatzacoalcos (Puerto México) are major Gulf of Mexico ports. Pacific ports include Acapulco de Juárez, Manzanillo, Mazatlán, and Salina Cruz. Lake Chapala, in the west, is the largest inland body of water. The Valley of Mexico contains several shallow lakes.

B

Climate

Mexico is bisected by the tropic of Cancer; therefore, the southern half is included in the Torrid Zone. In general, climate varies with elevation. The tierra caliente (hot land) includes the low coastal plains, extending from sea level to about 914 m (3,000 ft). Weather is extremely humid, with temperatures varying from 15.6° to 48.9° C (60° to 120° F). The tierra templada (temperate land) extends from about 914 to 1,830 m (3,000 to 6,000 ft) with average temperatures of 16.7° to 21.1° C (62° to 70° F). The tierra fría (cold land) extends from about 1,830 to 2,745 m (6,000 to 9,000 ft). The average temperature range is 15° to 17.2° C (59° to 63° F). The average temperatures in Mexico City for the months of January and July are 12.6° C (55° F) and 16.1° C (61° F), respectively. The average temperatures in Monterrey for the same months are 14.4° C (58° F) and 27.2° C (81° F).

The rainy season lasts from May to October. Although sections of southern Mexico receive about 990 to 3,000 mm (39 to 118 in) of rain a year, most of Mexico lacks adequate rainfall. Rainfall averages less than 635 mm (25 in) annually in the tierra templada, about 460 mm (18 in) in the tierra fría, and about 254 mm (10 in) in the semi-arid north. Annual precipitation averages for Mexico City and Monterrey are 750 mm (30 in) and 580 mm (23 in) respectively.