Introduction
Mexico City is one of the oldest continuously inhabited sites in the Americas. It is located within the central Mexican plateau, in the Valley of Mexico, on the former bed of lake Texcoco (elevation 7,400 feet) and is surrounded by mountains over 5000m high, Its city centre (the Zocalo) was built on the site of the Aztec capital site Tenochtitlán.
The Aztec city was built on a one-square mile island surrounded by an enormous shallow lake. By the early 1500's, the city was the hub of a powerful commercial and military empire, stretching from Texas to Honduras. A city of magnificent palaces, temples and markets, it was inhabited by around 200,000 people.
Then, in 1519, a band of just 400 Spaniards led by Hernán Cortés, confronted and conquered the mighty Aztec city. The Spaniards built a colonial capital on the site of Tenochtitlán, launching a period of 300 years of European conquest and colonization.
The conquerors divided the central area among themselves and relegated the defeated to the periphery. It soon became the most important city in the Americas, its centre a well laid-out collection of homes, public buildings, churches and convents.
In 1821 Mexico gained independence from Spain under Augustin de Iturbide, and was briefly held by American and French forces before revolution in the 1910s.
The 1920s saw plans for the urbanization of Mexico City initiated. As mills and factories spread, so more and more people were attracted to the city. Between 1930 and 1950, the population more than doubled, a pattern of rapid growth that has continued to the present day.
Like many of the world's 'megacities', Mexico City exhibits many of the problems of unchecked growth : unplanned and haphazard development, severe pollution, inadequate housing and services, high population densities and a generally poor quality of life for most residents.
Demographic impact
Mexico City's urbanization has been at a rate far in excess of anything experienced in the developed world. In 1940, the population was around 1.5 million. By 1970 this was 9m million and in 1990, about 15 million. Some estimates suggested Mexico City's population could top 30m by the year 2000, although it now appears to be more like 16-22 million. It is notoriously difficult to gauge the city's population accurately.
Even so, the rate of increase is massive, with 1,000 migrants arriving a day from urban areas. The majority of the migrants tend to by young males, leading to an imbalance in the population structure. Population density in some parts of the city reaches 500/ha.
Social impact
As the city's population has increased, people have tended to remain in similar areas, leading to a characteristic land-use pattern as shown in the introduction. The wealthiest districts are in the west, while developers sold large tracts of unserviced land in the east to low-income families.
In 1954 the Federal District forbade further subdivision of land within the city limits, leading to informal settlements in Naucalpan (W), Ecatepec (N) and Netzahualcoyotl (E). However, there is still a desperate shortage of dwellings - in 1994 is was estimated around 800,000 houses were required.
Access to healthcare attracts many to the city in the first place but there is uneven distribution of facilities, with most hospitals and clinics found in the centre and west. The social security system does not cover most who work in the informal sector, so many can scarce afford medical bills.
Some 60% of Mexico City's population live in what were originally illegal settlements. Much is poor quality and high density with few services.
The government does little to change this situation. Newcomers are treated as transients from rural areas who have strayed temporarily into town. they are described as 'marginal', belonging neither to the urban economy, nor to the place where they live. This supposed impermanence gives the authorities an excuse not to provide the slum dwellers with services.
Economic impact
Mexico City is very much a primate city, producing 28% of the the country's industrial output, 49% of manufacturing and 68% of financial services
There are well over 7 million economically active people within Mexico City, including 40% in the informal sector with low wages and no social security. The constant inflow of rural migrants inevitably end up as street vendors, unskilled workers in the clothing and show industries, or cleaners. The national minimum wage is $2.50, though most are pleased with any small wage they are given.
Foreign multi-national companies like Daewoo are attracted to Mexico City by the large cheap labour force. Tourism is another major foreign currency earner.
The inflow of rural migrants in search of employment makes the job situation acute, and unemployment is high.
Environmental impact
"Through the dense clouds of automotive exhaust the sun appeared only as a remote, flickering ball". That was how Marco Morelli described the air pollution on a typical day in Mexico City. In 1994, the World Health Organisation declared that air quality in Mexico City was only acceptable on 20 days in the year. The days when Mexico City was described as having "the world's most transparent air" are long gone. Nowadays, some 4 million vehicles, together with 40,000 factories pump over 12,000 tonnes of gases, pollutants and particulates a day.
Two million people suffer from diseases caused by air pollution, as well as increasing incidence of allergies, cardiovascular diseases and cancer. 98% of the population suffer from deformation and inflammation of the nasal passages.
The air pollution problem is exacerbated by the temperature inversions which occur when cold air sinks down from the surrounding mountains, trapping the pollutants below at ground level
Another contributing factor is the dumping of hazardous waste on open sites. The city produces 40% of all Mexico's hazardous waste, some 2.48 million tonnes pa. With no legal landfill sites and just 5 recyclers, waste in dumped in any available open space, for example Rincon Verde in the west. The site produces dangerous air and water pollution, when chemicals are leached into the water table.
Water supply is another problem. Mexico City consumes 60,000 litres of water per second, 80% of which is groundwater. Having overpumped the Mexico Valley aquifer, it is now necessary to pump water up to 180km from Cutzamala at much higher cost. Some 40% of water entering the city's supply system disappears en route, due to cracked and leaking pipes, illegal tampering and the lack of water meters. A vicious circle has developed, with the service so poor that the water companies cannot recoup their costs from users, and the derived income so low that the service can't be improved.
Conclusion
But what can be done about these problems? It is very difficult to control demographic change, although better education may help stem natural increase. The acute housing shortage has of course only one solution - build more houses. The problem is how and where. Between 1973 and 1976 the INFONAVIT housing agency commenced a building programme, and present state projects are geared towards self-help housing on the fringes of the city.
Services are slowly being built in former illegal settlements, but this needs to increase if the city is going to provide a better quality of life in the foreseeable future. The system where poorer families rely on charities for help with medical bills also needs to be reviewed. Perhaps if new developments were channelled into poorer areas this might help stimulate the economy.
Until there is city-wide regulation on planning, development will continue to be largely rapid and haphazard. The present system of 'zoning' and the independence of individual districts to control development is over-bureaucratic.
Finally, the environmental problems. Despite difficult parking conditions in the city, Mexicans remain wedded to their private cars. The Metro system is clean, fast and cheap, but congested and not extensive enough. Private cars, taxis and minibuses account for 34% of journeys but 85% of pollution. More rigorous controls on car ownership need to be enforced to help the city's appalling air pollution. In addition, industry must be controlled to lower emissions of air pollution and stop illegal dumping of waste.
Only by rigorous controls can Mexcio City's problems be managed.