Urbanization

Urbanization describes a shift toward a larger proportion of people living in urban settlements, along with changes in how land, work and services are organized. It is related to, but not identical with, urban population growth: the number of people in cities can rise without the urban share of a country's population increasing. Population growth, rural-to-urban migration, the extension of urban boundaries and the establishment of new urban centres can all contribute to urbanization. There is no single definition of an urban area used consistently by every country. Statistical systems may rely on population size, density, administrative boundaries, economic activity or access to services. Harmonized methods classify settlements along an urban–rural continuum to make comparisons more consistent, while complementing rather than replacing national definitions.

Urbanization has accompanied settled societies for millennia, but its pace and scale have varied. The Industrial Revolution accelerated it in many regions as factories, commerce and paid employment drew people toward towns and cities. In later periods, urban transitions have followed different paths: migration is one driver, but population increase within urban areas, changing settlement boundaries and the emergence of new centres also affect the urban share. The relationship between urbanization and economic development is not identical everywhere; a city’s population growth alone does not establish how widely its residents benefit from economic change.

Cities can bring workers, firms, institutions and customers into closer contact. This concentration can support specialized jobs, commerce and innovation, and can make shared infrastructure and services practical to provide. Yet population growth can outpace the construction of homes, transport, water and sanitation systems, schools and health services. Where housing is unaffordable or infrastructure is missing, residents may face overcrowding, insecure tenure or inadequate services. These conditions are not an inevitable result of urban life; they are shaped by access to land, public investment, governance and social inclusion.

The environmental effects of urbanization depend partly on settlement form and infrastructure. Dispersed growth can consume land and increase travel distances, while well-connected, compact neighbourhoods can make public transport and shared services more practical. Cities also face climate-related hazards, including heat and flooding, and urban development contributes to greenhouse-gas emissions. At the same time, local governments and communities can implement adaptation and emissions-reduction measures. Planning that considers housing, transport, public space, basic services and the needs of low-income and informal-settlement residents can help distribute benefits more fairly and reduce avoidable risks.