Urbanisation and Cities: KS3 Geography Explained

Urbanisation is the process by which a growing proportion of a population lives in cities rather than rural areas. In 1800 fewer than 5% of the world was urban; by 2007 more than half was; the UN projects two-thirds will be by 2050. Understanding why cities grow is core KS3 geography.

What drives urbanisation?

Geographers explain urban growth through push factors (reasons people leave rural areas) and pull factors (reasons people move to cities).

Push factors (rural) | Pull factors (urban)
Lack of employment beyond subsistence farming | More varied job opportunities, especially in manufacturing and services
Poverty; poor access to healthcare and education | Better hospitals, schools, and universities
Mechanisation of agriculture reducing farm jobs | Higher wages than rural work
Natural disasters (droughts, floods) reducing harvests | Bright lights, entertainment, and a wider social life
Conflict and insecurity in rural areas | Family and community networks already established in the city

In high-income countries (HICs) such as the UK, urbanisation mostly happened during the Industrial Revolution (roughly 1760–1850), as people moved from the countryside to factory cities like Manchester, Birmingham, and Leeds. In many low-income countries (LICs) and newly industrialising countries (NICs), rapid urbanisation is happening now — driven by rural poverty, agricultural change, and the growth of manufacturing and service industries.

What is a megacity?

A megacity is an urban area with a population of more than 10 million people. In 1950 there were only two megacities in the world: New York and Tokyo. By 2023 there are approximately 35, the majority in Asia, Africa, and South America.

Megacity | Country | Region | Approximate population (2023)
Tokyo | Japan | East Asia | ~37 million
Delhi | India | South Asia | ~33 million
Shanghai | China | East Asia | ~29 million
São Paulo | Brazil | South America | ~22 million
Mexico City | Mexico | Central America | ~22 million
Cairo | Egypt | North Africa/Middle East | ~21 million
London | United Kingdom | Europe | ~9 million (not yet a megacity)

The shift of megacity growth from Europe and North America to Asia, Africa, and Latin America reflects where the largest and most rapid urbanisation is now occurring.

What are the challenges of rapid urbanisation?

Rapid urbanisation — especially in low-income countries where city infrastructure cannot keep pace with population growth — creates serious challenges.

Housing and informal settlements: When people arrive faster than formal housing can be built, they construct informal housing from available materials on unoccupied land. These settlements — called favelas in Brazil, barrios in Latin America, slums or informal settlements more broadly — may house millions of people in cramped conditions without clean water, sanitation, or legal land title. Dharavi in Mumbai is one of Asia's largest informal settlements, with approximately one million residents in about 2 square kilometres. Rocinha in Rio de Janeiro is Brazil's largest favela, housing around 70,000 people on a steep hillside.

Infrastructure overload: Roads, public transport, water supply, sewage systems, and electricity networks are designed for specific populations. Rapid growth overwhelms them, leading to traffic congestion (Bangkok, São Paulo, and Mumbai are routinely cited among the world's most congested cities), water shortages, and unreliable electricity.

Pollution: Industrial growth concentrated in cities produces air and water pollution. In Delhi, seasonal air quality indices regularly exceed "hazardous" levels due to vehicle emissions, industrial activity, and agricultural burning. In many rapidly urbanising cities in Africa and Asia, rivers that flow through urban areas receive untreated sewage and industrial waste.

Unemployment and inequality: Not everyone who moves to a city finds formal employment. A large informal economy — street trading, day labour, domestic service — characterises many rapidly urbanising cities. While wages may be higher than in rural areas, the cost of living is also higher, and the gap between wealthy residents and the urban poor can be extreme.

How does urbanisation in high-income countries differ?

In high-income countries, urbanisation is largely complete and the challenges are different. Cities like London face:

Counter-urbanisation — people and businesses leaving the city centre for suburbs, smaller towns, or rural areas, enabled by cars and commuter rail links.

Gentrification — the movement of wealthier residents into previously low-income inner-city areas, raising property prices and displacing existing communities.

Urban regeneration — attempts to revitalise deprived or post-industrial areas; London's Docklands, Manchester's Salford Quays, and Glasgow's East End are examples.

Ageing infrastructure — Victorian-era water pipes, sewers, and transport networks in cities like London require constant maintenance and renewal.

A key concept here is suburbanisation — the growth of residential areas on the edges of cities. In the twentieth century, improvements in transport (cars, trains, buses) allowed people to live further from city centres. Green belts — designated areas of open land surrounding cities — were introduced in the UK in the 1930s and 1940s to limit suburban sprawl, but house prices in cities with strict green belts (such as London) have risen sharply as a result.

How can cities become more sustainable?

Sustainable urban development aims to meet the needs of current city residents without compromising future generations. Approaches include:

Public transport investment: reducing car use through reliable buses, trams, underground railways, and cycling infrastructure (the Netherlands — where approximately 25% of all urban trips are by bicycle — is often cited as a model).

Mixed land use: planning cities so that housing, shops, and workplaces are close together, reducing commuting distances and making walking viable.

Green infrastructure: parks, green roofs, urban trees, and waterways that reduce urban heat, absorb rainwater, and improve air quality.

Curitiba, Brazil, is a widely studied example of sustainable urban planning: its bus rapid transit system carries over 2 million passengers per day; its flood management uses parks as flood relief areas; its recycling scheme involves the urban poor exchanging waste for food. It demonstrates that urban sustainability is achievable even in lower-income contexts.

Frequently asked questions

What is the difference between urbanisation and urban growth?

Urban growth refers to an absolute increase in the number of people living in a city — a city grows in population. Urbanisation refers to an increase in the proportion of a country's total population living in urban areas. A country can experience urban growth (its cities get bigger) without experiencing urbanisation (if the rural population is growing just as fast). In practice, most countries experiencing rapid urban growth are also urbanising, because city populations are growing faster than rural ones.

What is counter-urbanisation and why does it happen?

Counter-urbanisation is the process by which people and businesses move out of large cities into smaller settlements or rural areas. It typically happens in wealthier countries once urbanisation is largely complete. Factors that drive it include: improved transport links that make commuting from rural areas viable; the rising cost of housing in cities; a preference for more space, lower crime, and a different quality of life; and, more recently, the growth of remote working that allows jobs to be done from anywhere. The COVID-19 pandemic of 2020 accelerated counter-urbanisation in the UK and other high-income countries.

What is a world city?

A world city (or global city) is an urban area that plays a disproportionately large role in the global economy and culture, serving as a major hub for finance, business, culture, media, and international organisations. London, New York, and Tokyo are generally considered the world's "alpha++" world cities — the highest tier. The concept was developed by sociologist Saskia Sassen in her 1991 book The Global City. World city status is not simply about population size: Frankfurt (Germany) and Zurich (Switzerland) are influential world cities despite being smaller than many megacities.

Why is the KS3 geography curriculum interested in urbanisation?

The KS3 geography curriculum asks students to understand human geography at different scales — local, national, and global — and to apply geographical concepts to real-world issues. Urbanisation is one of the most significant processes shaping the world today. Understanding why cities grow, who lives in them, what challenges they face, and how geography influences urban form and function develops the skills of spatial thinking, comparison across places, and understanding of human-environment interaction that are core geographical competencies.

For spatial thinking and SEEP analysis of urbanisation — explore KS3 geography support at aitutors.me.