Urbanization : A history

 The urbanization of the world population represents one of the most profound long-term shifts in human well-being, directly tied to economic development, health, and infrastructure access, according to data collected by the Our World In Data group.

The Historic Shift to an Urban World

The most striking development in population patterns over the last two centuries is the dramatic shift from predominantly rural living to urban dwelling. For the majority of human history, people lived in small communities.

• Astonishing Scale: Migration to towns and cities is largely confined to the past 200 years. By 1800, over 90% of the global population still resided in rural areas. The momentous milestone of having more people in urban areas than rural areas occurred only recently, in 2007. Today, over 4 billion people reside in urban settings.
• The Development Link: Urbanization is strongly associated with economic progress. There is a robust relationship between the share of a population living in urban areas and a country's average income (GDP per capita): as nations become wealthier, they tend to become more urbanized. This migration is linked to the historical process of structural transformation, where employment shifts away from agriculture toward industry, manufacturing, and services.
• The Future Trajectory: This trend shows no sign of stopping. By 2050, UN projections estimate that approximately two-thirds of the world's population, or close to 7 billion people, will live in urban areas.

Higher Standards, Deep Inequalities

In the context of global development, urbanization often correlates with improved living conditions, but this progress is deeply unequal, presenting one of the world's most stubborn remaining challenges.

The Positive Trend: Increased Living Standards

On average, urban populations enjoy higher living standards than their rural counterparts in key areas of development:

• Urban areas generally have greater access to electricity, improved sanitation, and improved drinking water.
• Child malnutrition rates tend to be lower in urban settings.

The development goal for cities, specifically Sustainable Development Goal (SDG) 11, focuses on making cities "inclusive, safe, resilient and sustainable". Achieving this relies on successfully translating economic growth into infrastructure and resources where the rapidly growing population needs them.

The Troubling Datapoint: The Urban Slum Challenge

A key development issue is that while cities represent economic opportunity, access to basic necessities within them is highly unequal. The most sobering statistic highlighted by Our World In Data is the prevalence of urban slum households.

• Prevalence: Just under one-in-four people living in urban areas globally reside in slum households.
• Definition of Deprivation: A slum household is defined by lacking one or more fundamental living conditions, including sufficient living space, durable housing, access to improved water and sanitation, and security of tenure (knowing they won't be evicted).
• Geographic Inequality: This problem is particularly severe in Sub-Saharan Africa, where, in many countries, over half of the urban population lives in slum households. In some instances, such as Chad, around 8 in 10 urban dwellers live in these deprived conditions.

The continued existence of such large-scale poverty and deprivation within burgeoning urban centers suggests that massive global progress in reducing extreme poverty worldwide has not yet translated into universal decent living standards within cities, particularly in Africa.

The Complexity of Measurement

Adding complexity to tracking this global trend is the fundamental issue of definition. The reported figures rely on highly variable criteria:

• Inconsistent Definitions: There is currently no universal definition of what constitutes an "urban area". Countries utilize vastly different standards, such as minimum population thresholds (which range from 200 inhabitants in Sweden to 50,000 in Japan) or criteria based on density or employment type.
• Conflicting Estimates: Because the widely cited UN global figures aggregate these inconsistent national definitions, cross-country comparisons should be viewed with caution. For example, the European Commission's harmonized definition (which includes towns) estimates that the total urban share was around 80% in 2020, significantly higher than the UN's estimate that just over half the world is urban.

Despite these conflicting estimates, the acceleration of urbanization at the national level remains clear, underscoring the urgency of addressing the accompanying development issues, particularly the challenge of providing adequate living conditions for billions of new urban residents.