1975 Megacities

In 1975, the world’s megacities—urban areas with populations exceeding 10 million—were rare, with only three cities typically recognized as such: Tokyo, New York City, and Mexico City. Tokyo, already the largest, had surged past 20 million inhabitants, reflecting Japan’s rapid postwar economic growth and urbanization. New York City, a long-established global metropolis, had a population of around 15 million in its metropolitan area, but was experiencing slower growth and even some decline in its urban core due to suburbanization and economic shifts. Mexico City, meanwhile, was in the midst of explosive growth, fueled by rural-to-urban migration and high birth rates, pushing its population past the 10 million mark for the first time. These megacities reflected different stages of urban development: Tokyo’s modern infrastructure and planning contrasted with Mexico City’s challenges of rapid, often unplanned expansion, while New York’s history as an immigrant gateway shaped its diverse urban landscape. The emergence of these megacities in 1975 signaled the beginning of a global trend, as urbanization accelerated across the developing world in subsequent decades.

Data from UN World Urbanization Prospects