Urbanisation: Trends, Causes and Megacities

Urbanisation is the process by which an increasing proportion of a country's population lives in towns and cities. It is the defining demographic trend of the past two centuries.

Key statistics:

• In 1800, approximately 3% of the world's population lived in urban areas
• By 1950, the figure had risen to 30%
• By 2007, the world passed the 50% threshold — for the first time, more than half the global population lived in urban areas
• By 2024, approximately 57% of the world's population is urban
• By 2050, the UN projects 68% urban — approximately 6.7 billion people in cities

The chart below shows the steep rise in the share of the world's population living in towns and cities since 1800.

The pattern is not uniform:

Stage	HIC trend	LIC/NEE trend
Past	Rapid urbanisation driven by industrialisation (UK: 19th century)	Largely rural; colonial economies were agricultural
Present	High levels of urbanisation (UK: ~84%; USA: ~83%); slow or no further growth; some counter-urbanisation	Rapid urbanisation underway; urban populations growing fast (sub-Saharan Africa, South/Southeast Asia)
Future	Stable or mild growth	Will account for nearly all global urban population growth to 2050

The urban transition in HICs largely occurred in the 19th and early 20th century. In LICs and NEEs, it is happening now — rapidly and on a much larger scale. By 2050, Africa and Asia are projected to add 2.5 billion more urban residents between them.

Urbanisation is driven by two interconnected forces: rural-to-urban migration (people moving from the countryside to cities) and natural increase (the birth rate in cities exceeding the death rate).

Push factors (reasons people leave rural areas):

Factor	Example
Agricultural mechanisation	Machines replace farm workers; there is less employment in the countryside
Rural poverty and low wages	Farm incomes are often subsistence level; limited opportunities for advancement
Natural hazards and crop failures	Drought, flood, and crop disease drive migration from vulnerable rural areas
Lack of services	Limited healthcare, schools, electricity, and internet access in remote areas
Conflict and insecurity	Rural areas in conflict zones become unsafe; people flee to cities

Pull factors (reasons people are attracted to cities):

Factor	Example
Employment opportunities	Cities have factories, services, and informal economic activity — more work than the countryside
Higher wages	Urban wages are typically higher than rural, even in informal sector work
Better services	Hospitals, schools, universities, transport, entertainment
Social networks	Communities of migrants from the same region establish themselves in cities, attracting further migration
Perceived better quality of life	Cities represent opportunity and modernity, even if reality is harsh for new arrivals

Natural increase contributes significantly to urban population growth in LICs, where birth rates are high and cities attract younger people of reproductive age.

A megacity is a city with a population of 10 million or more. The number of megacities has grown dramatically:

Year	Number of megacities
1950	2 (Tokyo, New York)
1990	10
2000	18
2024	37

Characteristics of megacity distribution:

• Most megacities are now in Asia — Tokyo (37m), Delhi (33m), Shanghai (29m), Dhaka (23m), Mumbai (21m), Beijing (22m), Osaka (19m), Karachi (17m) dominate the list
• A growing number are in South America — São Paulo (22m), Buenos Aires (16m), Lima (11m), Rio de Janeiro (13m), Bogotá (11m)
• Africa is rapidly generating new megacities — Lagos (15m), Cairo (22m), Kinshasa (16m); Dar es Salaam and Luanda growing rapidly towards the threshold
• Only a small and declining proportion of megacities are in high-income countries — Tokyo, New York (19m), Los Angeles (13m), Osaka — reflecting the shift of urban growth to the developing world

The map below shows the main megacities, clustered heavily in Asia with a growing number in Africa and South America.

World cities (also called global cities) (extra context — beyond AQA 8035 spec): a related concept — cities that function as major nodes in the global economy through finance, media, and corporate headquarters (e.g. London, New York, Tokyo, Singapore). Not all megacities are world cities.

The experience and character of urbanisation differs significantly between richer and poorer countries.

HIC urbanisation (e.g. UK):

• Began in the 18th–19th centuries driven by industrialisation (coal, iron, textiles)
• Now largely complete: the UK is 84% urban; growth has slowed
• Current trends: counter-urbanisation (people moving from large cities to suburbs or smaller towns) and reurbanisation (people returning to regenerated city centres)
• Cities are decentralising — out-of-town retail, business parks, edge cities
• Problems of established cities: traffic congestion, ageing infrastructure, social inequality, housing affordability

LIC/NEE urbanisation (e.g. Nigeria, India, Bangladesh):

• Began in the mid-to-late 20th century; accelerating rapidly
• Driven by rural-to-urban migration and high natural increase
• Infrastructure (housing, water, sanitation, roads, schools) cannot keep pace with population growth
• Slums and informal settlements develop as new arrivals build their own housing on unserviced land: 1 billion people globally live in informal settlements
• Both formal employment and informal economic activity (street vending, recycling, small manufacturing) characterise urban economies

Key difference: In HICs, urbanisation built wealth and improved living standards over time (with significant social costs). In LICs, urbanisation is occurring at such a rapid rate that infrastructure investment cannot keep up — producing informal settlements, overcrowding, and poor sanitation alongside economic growth.

These are key concepts for understanding urban trends in HICs.

Counter-urbanisation: Movement of people and businesses away from large urban centres to smaller towns, villages, and suburbs:

• Driven by: improved road and rail links (commuting possible from further away), rising city house prices, desire for larger homes and green space, remote and flexible working, crime and congestion in large cities
• Effect: growth of commuter settlements (settlements that expand as urban workers move in but commute for employment); rural areas and smaller towns grow; large cities lose population or grow slowly
• UK example: towns in the commuter belt around London (Guildford, Reading, St Albans) have grown significantly as London professionals relocate

Reurbanisation: Population and economic activity moving back into city centres following decline:

• Driven by: urban regeneration projects, new housing developments in former industrial areas, young professionals attracted to city-centre lifestyle amenities, gentrification
• UK examples: Salford Quays (Manchester), Canary Wharf and Docklands (London), Glasgow Merchant City — former industrial or dockland areas converted to high-value residential, office, and retail uses
• Reurbanisation can cause gentrification — rising property values and rents displace lower-income original residents

1. Confusing urbanisation with urban growth

Urbanisation is the increase in the proportion of people living in urban areas. Urban growth is the increase in the total number of urban residents. A city can grow in total population without urbanisation increasing (if rural population grows at the same rate). These terms are not interchangeable.

2. Stating that only migration causes urbanisation

Urbanisation is driven by both rural-to-urban migration and natural increase (births exceeding deaths within cities). In many LICs, natural increase within cities accounts for 40–60% of urban growth. Ignoring natural increase gives an incomplete answer.

3. Treating all megacities as equally wealthy

Many of the world's largest megacities are in LICs and NEEs with widespread poverty, large informal settlements, and poor infrastructure. Tokyo (Japan) and Dhaka (Bangladesh) are both megacities of 30+ million, but with vastly different characteristics. Never assume megacity = wealthy city.

4. Forgetting the definition of a megacity

A megacity has a population of 10 million or more. Memorise this. Common errors include using 1 million or 5 million as the threshold. Large cities with fewer than 10 million people (e.g. Rome, Sydney) are not megacities.

5. Describing counter-urbanisation only as "people moving to the countryside"

Counter-urbanisation includes movement to suburbs, smaller towns, market towns, and commuter settlements — not just rural villages. Most counter-urbanisers remain within daily commuting range of the city. Include the role of improved transport and remote working in driving this trend.