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How do population growth and rural-to-urban migration increase the size of cities?
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Crowds of people in Tokyo's Shibuya shopping district.
Cities increase in size through a combination of natural population growth and rural-to-urban migration, a process known as urbanization.12
Mechanisms of Growth
- Rural-to-Urban Migration: Historically, the industrialization of agriculture reduced the need for labor on farms, prompting a shift of the population toward urban centers in search of economic and cultural opportunities. This flow remains a primary driver of urban expansion, particularly in developing nations where rural-to-urban migration is a significant component of internal migration.23
- Natural Population Increase: Cities grow as their existing populations expand. In many developing countries, high overall birth rates contribute to rapid urban growth, with some city populations doubling in a decade or less.3
- Spatial Expansion: As urban populations rise, cities often expand their geographic footprint through urban sprawl. This involves the development of land for residential and infrastructure purposes, often extending into previously rural or natural areas to accommodate the need for housing and living space.4
While these factors drive growth, the resulting expansion often necessitates complex social and infrastructure planning to manage the increased demand for public health, housing, and utilities.2