high levels of pollution, poor and unsanitary housing conditions, and an inability
to provide adequate services to the rapidly growing population. Mexico City is
an example of a developing city that faces this spectrum of problems. Between
1940 and 1980 the population of the metropolitan area of Mexico City increased
by almost 12 million, growing from just under 2 million to well over 14 million
inhabitants. Most of this spectacular expansion was due to immigration from rural
villages, as millions of poor Mexicans moved to the capital seeking greater
employment opportunities, and settled insquatter settlements. The city’s indus-
trial base expanded to take advantage of the increasing supply of cheap labor,
especially in the cases of petrochemicals, steel manufacture, and durable goods.
Pollution from the dozens of large factories associated with this expansion plagued
the city’s residents for decades—from the 1960s to the 1990s Mexico City was
frequently ranked as having the worst air quality in the world. The city’s housing
market simply could not keep up with demand, and many of the new arrivals could
not afford housing in the urban area anyway. The result was a ring of poor neigh-
borhoods composed of shacks around the city, known locally asbarrios. Many of
these districts have no sewer systems, with electricity and treated water in short
supply. Many other cities in developing countries suffer from similar problems,
due to rates of urban growth that challenge the most dedicated urban planners.354 Urbanization