THE TWENTIETH CENTURY has earned many designations, among them the "Century of Total Warfare," the "American Century," and, of course, the "Atomic Age." The most fitting title of all, however, may be the "Century of the City," named for the revolution that started some fifty years ago which is still transforming the international scene into an urban world today. As a consequence of this urbanization, cities will house more than half of the world's population by the first decades of the new millennium. Cities no longer merely present local problems to be swept under domestic rugs: as urban populations overwhelm nations, they become catalysts for radical change in the world's social, economic, and political life, creating a collective global challenge. Given the international implications of urban problems, an international approach to addressing urban problems can not only improve living standards for the citizens of the world but also prevent potential international crises.
Although the dynamic of this "silent revolution" of urbanization is difficult to capture with the broad brush of statistics, a few reference points help establish its scale. Just half a century ago, urbanization had permeated most heavily industrialized cities, but nearly 90 percent of the world's population still lived in rural areas. The change in the following decades affected every nation, especially the developing countries, where, by the end of the century, the percentage of the national population in urban areas will almost triple. In 1950, this proportion stood at 13 percent. By 1980 it had soared to 38 percent. By the year 2000, it is expected to reach 48 percent, and, by 2020, it is projected to top the 50 percent mark.
Vast differences in the degree of urbanization in the developing world still exist; Latin America, for example, is largely urbanized while Africa is not. But as a group, the urban centers of developing nations will more than double in the next 25 years. Every year, 20 new cities attain the population size of Washington, DC--a comparison that fails to even account for the unprecedented size attained by many of these new urban agglomerations. By the end of the 21st century, it is expected that more people will live in the dense cities of developing countries than are alive in the entire world today.
The global trend of migration to the cities emerged from the rapid and sometimes destructive economic changes that were faced at mid-century by both urban and rural populations throughout the world. In particular, the stress on industrialization in the development policies of nations led to a deemphasis of the agricultural sector. Billions of people abandoned rural villages and farming communities to seek employment and the elusive promise of a better life in the cities. While labor flowed to factories and manufacturing, agricultural development was overlooked and ignored by government policy. This bias in favor of industrialization inadvertently subsidized urban growth even as it hollowed out the agricultural capacity necessary to support the new city dwellers. Many nations once sufficient in agricultural production now face deficiencies as an outcome of these policies. Just a generation or two ago, Algeria exported its surpluses of wheat, but now it must import wheat to feed its own population. Likewise, Indonesia was self-sufficient in rice, but now must import more than two-thirds of its needs. Zaire, also once a net food exporter, now totters on the brink of mass starvation.
The results of this rapid and unprecedented urbanization are apparent in both rich countries and poor countries, but especially in poor ones. Given the tremendous influxes and concentrations of people, cities suffer from inadequate shelter provisions. More than a billion urban dwellers are homeless or live in inadequate, unsafe housing. (Though definitions of adequate shelter vary, all definitions include the criteria of appropriate space, security, ventilation, water, sanitation, at an affordable cost. …