Acapulco / G. Alvarez, Mexico
Aerop. Internacional Monterrey, N. L.,
Mexico
Aguascalientes, Ags., Mexico
Bahias De Huatulco, Mexico
Cuernavaca, Mor., Mexico
Ciudad Del Carmen, Mexico
Culiacan, Sin., Mexico
Chetumal, Q. Roo, Mexico
Santa Rosalia, B. C. S., Mexico
Campeche, Camp., Mexico
Ciudad Juarez International, Mexico
Chihuahua International Airport, Mexico
Ciudad Victoria Airport, Mexico
Cozumel Civ / Mil, Mexico
Durango Airport, Mexico
Tepic, Nay., Mexico
Don Miguel / Guadalaj, Mexico
Guaymas International Airport, Mexico
Hermosillo, Son., Mexico
Colima, Mexico
Saltillo, Coah., Mexico
Lazaro Cardenas, Mexico
Los Mochis Airport, Mexico
Del Bajio / Leon, Mexico
La Paz International Airport, Mexico
Loreto, B. C. S., Mexico
Matamoros International, Mexico
Aerop. Internacional Merida, Yuc, Mexico
Mexicali International Airport, Mexico
Morelia New, Mexico
Minatitlan, Mexico
Monclova, Coah., Mexico
Mexico City / Licenci, Mexico
Monterrey / Gen Maria, Mexico
Mazatlan / G. Buelna, Mexico
Nuevo Laredo International, Mexico
Oaxaca / Xoxocotlan, Mexico
Poza Rica / Palizada, Mexico
Puebla, Pue., Mexico
Piedras Negras, Coah., Mexico
Uruapan / Gen Rayon, Mexico
Puerto Vallarta / Lic, Mexico
Puerto Escondido, Mexico
Queretaro, Qro., Mexico
Reynosa International Airport, Mexico
San Jose Del Cabo, Mexico
San Luis Potosi, S. L. P., Mexico
Torreon, Coah., Mexico
Tuxtla Gutierrez, Chis., Mexico
Tijuana International Airport, Mexico
Tulancingo, Mexico
Tampico / Gen Fj Mina, Mexico
Toluca / Jose Maria, Mexico
Tapachula, Mexico
Cancun International Airport, Mexico
Villahermosa, Mexico
Gen. Heriberto Jara, Mexico
Zacatecas Airport, Mexico
Ixtapa-Zihuatanejo, Mexico
Manzanillo International, Mexico
Zapopan Military, Mexico
Location: Middle America, bordering the Caribbean Sea and
the Gulf of Mexico, between Belize and the US and bordering the
North Pacific Ocean, between Guatemala and the US
Geographic coordinates: 23 00 N, 102 00 W
Map references: North America
Area:
total: 1,972,550 sq km
land: 1,923,040 sq km
water: 49,510 sq km
Area - comparative: slightly less than three times the size
of Texas
Land boundaries:
total: 4,538 km
border countries: Belize 250 km, Guatemala 962 km, US 3,326
km
Coastline: 9,330 km
Maritime claims:
contiguous zone: 24 nm
continental shelf: 200 nm or to the edge of the continental
margin
exclusive economic zone: 200 nm
territorial sea: 12 nm
Climate: varies from tropical to desert
Terrain: high, rugged mountains; low coastal plains; high
plateaus; desert
Elevation extremes:
lowest point: Laguna Salada -10 m
highest point: Volcan Pico de Orizaba 5,700 m
Natural resources: petroleum, silver, copper, gold, lead,
zinc, natural gas, timber
Land use:
arable land: 12%
permanent crops: 1%
permanent pastures: 39%
forests and woodland: 26%
other: 22% (1993 est.)
Irrigated land: 61,000 sq km (1993 est.)
Natural hazards: tsunamis along the Pacific coast, volcanoes
and destructive earthquakes in the center and south, and hurricanes
on the Gulf of Mexico and Caribbean coasts
Environment - current issues: natural fresh water resources
scarce and polluted in north, inaccessible and poor quality in center
and extreme southeast; raw sewage and industrial effluents polluting
rivers in urban areas; deforestation; widespread erosion; desertification;
serious air pollution in the national capital and urban centers
along US-Mexico border
Environment - international agreements:
party to: Biodiversity, Climate Change, Desertification,
Endangered Species, Hazardous Wastes, Law of the Sea, Marine Dumping,
Marine Life Conservation, Nuclear Test Ban, Ozone Layer Protection,
Ship Pollution, Wetlands, Whaling
signed, but not ratified: Climate Change-Kyoto Protocol
Geography - note: strategic location on southern border
of US
Geography
Mexico, known as United Mexican States (Estados Unidos Mexicanos
in Spanish). The nation's capital, Mexico City, is one of the largest
cities in the world.
Mexico is bordered by the United States on the north, the Pacific
Ocean on the west, the Gulf of Mexico and the Caribbean Sea on the
east, and Guatemala and Belize on the south.
It is characterized by an extraordinary diversity in topography
and climate and is crossed by two major mountain chains, the Sierra
Madre Occidental and the Sierra Madre Oriental.
Climate
The climate throughout Mexico is characterized by high temperatures
and moderate to low rainfall. The highland climates vary considerably
with elevation, but the central plateau generally has a moderate
climate with few extremes of hot or cold.
Mexico City, for example, has an average July temperature of 17°
C (63° F) and an average January temperature of 12° C (54° F). Cities
at lower elevations on the plateau have somewhat warmer climates.
Mexico is the northernmost country of Latin America. It lies just
south of the United States. The Rio Grande forms about two-thirds
of the boundary between Mexico and the United States.
Among all the countries of the Western Hemisphere, only the United
States and Brazil have more people than Mexico. Mexico City is the
capital and largest city of Mexico.
It also has one of the world's largest metropolitan area populations.
Mexico
Geography
Size: 1,972,550 square kilometers--third largest
nation in Latin America (after Brazil and Argentina).
Topography: Various massive mountain ranges including
Sierra Madre Occidental in west, Sierra Madre Oriental in east,
Cordillera Neovolcánica in center, and Sierra Madre del Sur in south;
lowlands largely along coasts and in Yucatan Peninsula. Interior
of country high plateau. Frequent seismic activity.
Drainage: Few navigable rivers. Most rivers short
and run from mountain ranges to coast.
Climate: Great variations owing to considerable
north-south extension and variations in altitude. Most of country
has two seasons: wet (June-September) and dry (October-April). Generally
low rainfall in interior and north. Abundant rainfall along east
coast, in south, and in Yucatan Peninsula.
Society
Population: Estimated population of 94.8 million
persons in mid-1996. Annual rate of growth 1.96 percent.
Language: Spanish official language, spoken by
nearly all. About 8 percent of population speaks an indigenous language;
most of these people speak Spanish as second language. Knowledge
of English increasing rapidly, especially among business people,
the middle class, returned emigrants, and the young.
Ethnic Groups: Predominantly mestizo society (60
percent); 30 percent indigenous; 9 percent European; 1 percent other.
Education and Literacy: Secretariat of Public
Education has overall responsibility for all levels of education
system. Compulsory education to age sixteen; public education free.
Government distributes free textbooks and workbooks to all primary
schools. Official literacy rate in 1990 was 88 percent.
Health and Welfare: Health care personnel and
facilities generally concentrated in urban areas; care in rural
areas confined to understaffed clinics operated mostly by medical
graduate students. Life expectancy in 1996 estimated at seventy-three
years. Infant mortality twenty-six per 1,000 live births. Leading
causes of death infections, parasitic diseases, and respiratory
and circulatory system failures.
Religion: About 90 percent of population Roman
Catholic, according to 1990 census. Protestants (about 6 percent)
ranked second. Number of Protestants has increased dramatically
since 1960s, especially in southern states.
Data as of June 1996
Mexico
The Society and Its Environment
PROFOUND CHANGES OCCURRED IN Mexican society during the second
half of the twentieth century. A sharp decline in mortality levels,
coupled with fertility rates that remained relatively high until
the mid-1970s, produced a massive population increase. Indeed, the
1990 census total of approximately 81 million Mexicans was more
than triple the figure recorded forty years earlier. Mexico's stagnant
agricultural sector could not absorb the millions of additional
workers, triggering a steady migration to the cities. As a result,
Mexico shifted from a predominantly rural to a heavily urban society.
Because of the lack of available housing, migrants generally clustered
on the periphery of Mexico City and other major urban centers. The
local infrastructure often could not keep pace with such growth,
resulting in serious environmental concerns.
Despite the massive problems caused by the rapid population shift,
successive Mexican governments could point to notable accomplishments
in improving the quality of life of their citizens. In the years
after World War II, the percentage of deaths caused by infectious,
parasitic, and respiratory illnesses fell dramatically. Both the
number and percentage of Mexicans with access to basic services
such as running water and electricity grew substantially. Literacy
and educational levels continued to climb.
The benefits of modernization were not equally distributed, however.
Residents of southern Mexico consistently trailed the rest of the
country in "quality-of-life" indicators. Urban workers in the informal
sector of the economy did not have access to the same level of health
care as their counterparts in the formal sector and did not qualify
for retirement or pension payments. Income distribution had become
increasingly skewed in favor of the wealthiest sectors of society.
Mexican policy makers thus faced the difficult challenge of ensuring
economic growth while also confronting the persistence of poverty.
Physical Setting
Mexico's total area covers 1,972,550 square kilometers, including
approximately 6,000 square kilometers of islands in the Pacific
Ocean, Gulf of Mexico, Caribbean Sea, and Gulf of California . On
its north, Mexico shares a 3,326-kilometer border with the United
States. The meandering Río Bravo del Norte (known as the Rio Grande
in the United States) defines the border from Ciudad Juárez east
to the Gulf of Mexico. A series of natural and artificial markers
delineate the United States-Mexican border west from Ciudad Juárez
to the Pacific Ocean. On its south, Mexico shares an 871-kilometer
border with Guatemala and a 251-kilometer border with Belize. Mexico
has a 10,143-kilometer coastline, of which 7,338 kilometers face
the Pacific Ocean and the Gulf of California, and the remaining
2,805 kilometers front the Gulf of Mexico and the Caribbean Sea.
Mexico's exclusive economic zone (EEZ), which extends 200 nautical
miles off each coast, covers approximately 2.7 million square kilometers.
The landmass of Mexico dramatically narrows as it moves in a southeasterly
direction from the United States border and then abruptly curves
northward before ending in the 500-kilometer-long Yucatan Peninsula.
Indeed, the capital of Yucatán State, Mérida, is farther north than
Mexico City or Guadalajara.
Data as of June 1996
Mexico
Topography and Drainage
Two prominent mountain ranges--the Sierra Madre Occidental and
the Sierra Madre Oriental--define northern Mexico. Both are extensions
of ranges found in the United States. The Sierra Madre Occidental
on the west is a continuation of California's Sierra Nevada (with
a break in southeastern California and extreme northern Mexico),
and the Sierra Madre Oriental on the east is a southward extension
of the Rocky Mountains of New Mexico and Texas. Between these two
ranges lies the Mexican altiplano (high plain), a southern continuation
of the Great Basin and high deserts that spread over much of the
western United States.
Beginning approximately fifty kilometers from the United States
border, the Sierra Madre Occidental extends 1,250 kilometers south
to the Río Santiago, where it merges with the Cordillera Neovolcánica
range that runs east-west across central Mexico. The Sierra Madre
Occidental lies approximately 300 kilometers inland from the west
coast of Mexico at its northern end but approaches to within fifty
kilometers of the coast near the Cordillera Neovolcánica. The northwest
coastal plain is the name given the lowland area between the Sierra
Madre Occidental and the Gulf of California. The Sierra Madre Occidental
averages 2,250 meters in elevation, with peaks reaching 3,000 meters.
The Sierra Madre Oriental starts at the Big Bend region of the
Texas-Mexico border and continues 1,350 kilometers until reaching
Cofre de Perote, one of the major peaks of the Cordi-llera Neovolcánica.
As is the case with the Sierra Madre Occidental, the Sierra Madre
Oriental comes progressively closer to the coastline as it approaches
its southern terminus, reaching to within seventy-five kilometers
of the Gulf of Mexico. The northeast coastal plain extends from
the eastern slope of the Sierra Madre Oriental to the Gulf of Mexico.
The median elevation of the Sierra Madre Oriental is 2,200 meters,
with some peaks at 3,000 meters.
The Mexican altiplano, stretching from the United States border
to the Cordillera Neovolcánica, occupies the vast expanse of land
between the eastern and western sierra madres. A low east-west range
divides the altiplano into northern and southern sections. These
two sections, previously called the Mesa del Norte and Mesa Central,
are now regarded by geographers as sections of one altiplano. The
northern altiplano averages 1,100 meters in elevation and continues
south from the Río Bravo del Norte through the states of Zacatecas
and San Luis Potosí. Various narrow, isolated ridges cross the plateaus
of the northern altiplano. Numerous depressions dot the region,
the largest of which is the Bolsón de Mapimí. The southern altiplano
is higher than its northern counterpart, averaging 2,000 meters
in elevation. The southern altiplano contains numerous valleys originally
formed by ancient lakes. Several of Mexico's most prominent cities,
including Mexico City and Guadalajara, are located in the valleys
of the southern altiplano.
One other significant mountain range, the California system, cuts
across the landscape of the northern half of Mexico. A southern
extension of the California coastal ranges that parallel California's
coast, the Mexican portion of the California system extends from
the United States border to the southern tip of the Baja Peninsula,
a distance of 1,430 kilometers. Peaks in the California system range
in altitude from 2,200 meters in the north to only 250 meters near
La Paz in the south. Narrow lowlands are found on the Pacific Ocean
and the Gulf of California sides of the mountains.
The Cordillera Neovolcánica is a belt 900 kilometers long and
130 kilometers wide, extending from the Pacific Ocean to the Gulf
of Mexico. The Cordillera Neovolcánica begins at the Río Grande
de Santiago and continues south to Colima, where it turns east along
the nineteenth parallel to the central portion of the state of Veracruz.
The region is distinguished by considerable seismic activity and
contains Mexico's highest volcanic peaks. This range contains three
peaks exceeding 5,000 meters: Pico de Orizaba (Citlaltépetl)--the
third highest mountain in North America--and Popocatépetl and Iztaccíhuatl
near Mexico City. The Cordillera Neovolcánica is regarded as the
geological dividing line between North America and Central America.
Several important mountain ranges dominate the landscape of southern
and southeastern Mexico. The Sierra Madre del Sur extends 1,200
kilometers along Mexico's southern coast from the southwestern part
of the Cordillera Neovolcánica to the nearly flat isthmus of Tehuantepec.
Mountains in this range average 2,000 meters in elevation. The range
averages 100 kilometers in width, but widens to 150 kilometers in
the state of Oaxaca. The narrow southwest coastal plain extends
from the Sierra Madre del Sur to the Pacific Ocean. The Sierra Madre
de Oaxaca begins at Pico de Orizaba and extends in a southeasterly
direction for 300 kilometers until reaching the isthmus of Tehuantepec.
Peaks in the Sierra Madre de Oaxaca average 2,500 meters in elevation,
with some peaks exceeding 3,000 meters. South of the isthmus of
Tehuantepec, the Sierra Madre de Chiapas runs 280 kilometers along
the Pacific Coast from the Oaxaca-Chiapas border to Mexico's border
with Guatemala. Although average elevation is only 1,500 meters,
one peak--Volcán de Tacuma--exceeds 4,000 meters in elevation. Finally,
the Meseta Central de Chiapas extends 250 kilometers through the
central part of Chiapas to Guatemala. The average height of peaks
of the Meseta Central de Chiapas is 2,000 meters. The Chiapas central
valley separates the Meseta Central de Chiapas and the Sierra Madre
de Chiapas.
Mexico has nearly 150 rivers, two-thirds of which empty into the
Pacific Ocean and the remainder of which flow into the Gulf of Mexico
or the Caribbean Sea. Despite this apparent abundance of water,
water volume is unevenly distributed throughout the country. Indeed,
five rivers--the Usumacinta, Grijalva, Papaloapán, Coatzacoalcos,
and Pánuco--account for 52 percent of Mexico's average annual volume
of surface water. All five rivers flow into the Gulf of Mexico;
only the Río Pánuco is outside southeastern Mexico, which contains
approximately 15 percent of national territory and 12 percent of
the national population. In contrast, northern and central Mexico,
with 47 percent of the national area and almost 60 percent of Mexico's
population, have less than 10 percent of the country's water resources.
Seismic Activity
Situated atop three of the large tectonic plates that constitute
the earth's surface, Mexico is one of the most seismologically active
regions on earth. The motion of these plates causes earthquakes
and volcanic activity.
Most of the Mexican landmass rests on the westward moving North
American plate. The Pacific Ocean floor off southern Mexico, however,
is being carried northeast by the underlying motion of the Cocos
plate. Ocean floor material is relatively dense; when it strikes
the lighter granite of the Mexican landmass, the ocean floor is
forced under the landmass, creating the deep Middle American trench
that lies off Mexico's southern coast. The westward moving land
atop the North American plate is slowed and crumpled where it meets
the Cocos plate, creating the mountain ranges of southern Mexico.
The subduction of the Cocos plate accounts for the frequency of
earthquakes near Mexico's southern coast. As the rocks constituting
the ocean floor are forced down, they melt, and the molten material
is forced up through weaknesses in the surface rock, creating the
volcanoes in the Cordillera Neovolcánica across central Mexico.
Areas off Mexico's coastline on the Gulf of California, including
the Baja California Peninsula, are riding northwestward on the Pacific
plate. Rather than one plate subducting, the Pacific and North American
plates grind past each other, creating a slip fault that is the
southern extension of the San Andreas fault in California. Motion
along this fault in the past pulled Baja California away from the
coast, creating the Gulf of California. Continued motion along this
fault is the source of earthquakes in western Mexico.
Mexico has a long history of destructive earthquakes and volcanic
eruptions. In September 1985, an earthquake measuring 8.1 on the
Richter scale and centered in the subduction zone off Acapulco killed
more than 4,000 people in Mexico City, more than 300 kilometers
away. Volcán de Colima, south of Guadalajara, erupted in 1994, and
El Chichón, in southern Mexico, underwent a violent eruption in
1983. Paricutín in northwest Mexico began as puffs of smoke in a
cornfield in 1943; a decade later the volcano was 2,700 meters high.
Although dormant for decades, Popocatépetl and Ixtaccíhuatl ("smoking
warrior" and "white lady," respectively, in Náhuatl) occasionally
send out puffs of smoke clearly visible in Mexico City, a reminder
to the capital's inhabitants that volcanic activity is near. Popocatépetl
showed renewed activity in 1995 and 1996, forcing the evacuation
of several nearby villages and causing concern by seismologists
and government officials about the effect that a large-scale eruption
might have on the heavily populated region nearby.
Data as of June 1996
Mexico
Climate
The Tropic of Cancer effectively divides the country into temperate
and tropical zones. Land north of the twenty-fourth parallel experiences
cooler temperatures during the winter months. South of the twenty-fourth
parallel, temperatures are fairly constant year round and vary solely
as a function of elevation.
Areas south of the twentieth-fourth parallel with elevations up
to 1,000 meters (the southern parts of both coastal plains as well
as the Yucatan Peninsula), have a yearly median temperature between
24°C and 28°C. Temperatures here remain high throughout
the year, with only a 5°C difference between winter and summer
median temperatures. Although low-lying areas north of the twentieth-fourth
parallel are hot and humid during the summer, they generally have
lower yearly temperature averages (from 20°C to 24°C) because
of more moderate conditions during the winter.
Between 1,000 and 2,000 meters, one encounters yearly average
temperatures between 16°C and 20°C. Towns and cities at
this elevation south of the twenty-fourth parallel have relatively
constant, pleasant temperatures throughout the year, whereas more
northerly locations experience sizeable seasonal variations. Above
2,000 meters, temperatures drop as low as an average yearly range
between 8°C and 12°C in the Cordillera Neovolcánica. At
2,300 meters, Mexico City has a yearly median temperature of 15°C
with pleasant summers and mild winters. Average daily highs and
lows for May, the warmest month, are 26°C and 12°C, and
average daily highs and lows for January, the coldest month, are
19°C and 6°C.
Rainfall varies widely both by location and season. Arid or semiarid
conditions are encountered in the Baja Peninsula, the northwestern
state of Sonora, the northern altiplano, and significant portions
of the southern altiplano. Rainfall in these regions averages between
300 and 600 millimeters per year. Average rainfall totals are between
600 and 1,000 millimeters in most of the year in most of the major
populated areas of the southern altiplano, including Mexico City
and Guadalajara. Low-lying areas along the Gulf of Mexico receive
in excess of 1,000 millimeters of rainfall in an average year, with
the wettest region being the southeastern state of Tabasco, which
typically receives approximately 2,000 millimeters of rainfall on
an annual basis. Parts of the northern altiplano and high peaks
in the Sierra Madre Occidental and the Sierra Madre Oriental occasionally
receive significant snowfalls.
Mexico has pronounced wet and dry seasons. Most of the country
experiences a rainy season from June to mid-October and significantly
less rain during the remainder of the year. February and July generally
are the driest and wettest months, respectively. Mexico City, for
example, receives an average of only 5 millimeters of rain during
February but more than 160 millimeters in July. Coastal areas, especially
those along the Gulf of Mexico, experience the largest amounts of
rain in September. Tabasco typically records more than 300 millimeters
of rain during that month. A small coastal area of northwestern
coastal Mexico around Tijuana has a Mediterranean climate with considerable
coastal fog and a rainy season that occurs in winter.
Mexico lies squarely within the hurricane belt, and all regions
of both coasts are susceptible to these storms from June through
November. Hurricanes on the Pacific coast are less frequent and
often less violent than those affecting Mexico's eastern coastline.
Several hurricanes per year strike the Caribbean and Gulf of Mexico
coastline, however, and these storms bring high winds, heavy rain,
extensive damage, and occasional loss of life. Hurricane Hugo passed
directly over Cancún in September 1989, with winds in excess of
200 kilometers per hour producing major damage to hotels in the
resort area. In September 1988, Hurricane Gilbert struck northeast
Mexico. Flooding from the heavy rain in that storm killed dozens
in the Monterrey area and caused extensive damage to livestock and
vegetable crops.
Environmental Conditions
Mexico faces significant environmental challenges affecting almost
every section of the country. Vast expanses of southern and southeastern
tropical forests have been denuded for cattle-raising and agriculture.
For example, tropical forests covered almost half of the state of
Tabasco in 1940 but less than 10 percent by the late 1980s. During
the same period, pastureland increased from 20 to 60 percent of
the state's total area. Analysts reported similar conditions in
other tropical sections of Mexico. Deforestation has contributed
to serious levels of soil erosion nationwide. In 1985 the government
classified almost 17 percent of all land as totally eroded, 31 percent
in an accelerated state of erosion, and 38 percent demonstrating
signs of incipient erosion.
Soil destruction is particularly pronounced in the north and northwest,
with more than 60 percent of land considered in a total or accelerated
state of erosion. Fragile because of its semiarid and arid character,
the soil of the region has become increasingly damaged through excessive
cattle-raising and irrigation with waters containing high levels
of salinity. The result is a mounting problem of desertification
throughout the region.
Mexico's vast coastline faces a different, but no less difficult,
series of environmental problems. For example, inadequately regulated
petroleum exploitation in the Coatzacoalcos-Minatitlán zone in the
Gulf of Mexico has caused serious damage to the waters and fisheries
of Río Coatzacoalcos. The deadly explosion that racked a working-class
neighborhood in Guadalajara in April 1992 serves as an appropriate
symbol of environmental damage in Mexico. More than 1,000 barrels
of gasoline seeped from a corroded Mexican Petroleum (Petróleos
Mexicanos--Pemex) pipeline into the municipal sewer system, where
it combined with gases and industrial residuals to produce a massive
explosion that killed 190 persons and injured nearly 1,500 others.
Mexico City confronts authorities with perhaps their most daunting
environmental challenge. Geography and extreme population levels
have combined to produce one of the world's most polluted urban
areas. Mexico City sits in a valley surrounded on three sides by
mountains, which serve to trap contaminants produced by the metropolitan
area's 15 million residents. One government study in the late 1980s
determined that nearly 5 million tons of contaminants were emitted
annually in the atmosphere, a tenfold increase over the previous
decade. Carbons and hydrocarbons from the region's more than 3 million
vehicles account for approximately 80 percent of these contaminants,
with another 15 percent, primarily of sulfur and nitrogen, coming
from industrial plants. During the dry winter months, untreated
fecal matter also becomes airborne. The resulting dangerous mix
is responsible for a wide range of respiratory illnesses. One study
of twelve urban areas worldwide in the mid-1980s concluded that
the residents of Mexico City had the highest levels of lead and
cadmium in their blood. The volume of pollutants from Mexico City
has damaged the surrounding ecosystem as well. For example, wastewater
from Mexico City that flows north and is used for irrigation in
the state of Hidalgo has been linked to congenital birth defects
and high levels of gastrointestinal diseases in that state.
Beginning in the mid-1980s, the government enacted numerous antipollution
policies in Mexico City with varied degrees of success. Measures
such as vehicle emissions inspections, the introduction of unleaded
gasoline, and the installation of catalytic converters on new vehicles
helped reduce pollution generated by trucks and buses. In contrast,
one of the government's most prominent actions, the No Driving Day
program, may have inadvertently contributed to higher pollution
levels. Under the program, metropolitan area residents were prohibited
from driving their vehicles one day each work week based on the
last number of their license plate. However, those with the resources
to do so purchased additional automobiles to use on the day their
principal vehicle was prohibited from driving, thus adding to the
region's vehicle stock. Thermal inversions reached such dangerous
levels at various times in the mid-1990s that the government declared
pollution emergencies, necessitating sharp temporary cutbacks in
vehicle use and industrial production.
Data as of June 1996
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