Population, Water and Sustainability in American Mega-cities: Mexico City, New York and São Paulo

The paper compares the three largest mega-cities of the Americas (Mexico City, New York and São Paulo), in terms of population size, growth history, density and age structure, and in terms of access to water, conflicts over the use of water, and distance from which water is transported, in order to: identify the demographic components of water availability and sustainability of these urban regions; call attention to the primacy of population mobility and distribution as central issues; assess the prospects of achieving balance between population characteristics and access to water; and consider the case for ecological-economic zoning as a tool for sustainability.
The Americas, and their three most populous countries, are not among the world’s crisis zones in terms of water availability. The United States and Brazil, in particular, are water abundant; but even Mexico – at the national level – has reasonable water/population ratios. Their three largest mega-cities, however, illustrate a crucial fact regarding population and resources: where population is located vis-à-vis water supplies translates into periodic or long-term crises, and must be a fundamental issue to sustainability.