Causes & Patterns of Urbanisation
A Planet of City Dwellers
In 1950, only about 30% of people lived in towns and cities. By 2007 the world crossed a tipping point — for the first time in history, more than half of humanity was urban. Today the figure is around 57%, and the United Nations projects it will reach 68% by 2050. The next thirty years are expected to add more than 2 billion city dwellers, almost all of them in Asia and Africa. Urbanisation is one of the defining processes of our time, reshaping where people live, how they work and the pressures placed on the environment.
Why Are Cities Growing?
Two processes drive urban growth. The first is rural-urban migration — people moving from villages to cities. The second is natural increase, where the urban population grows because births outnumber deaths inside the city itself. Migrants are typically young adults of working age, so once they arrive they have children, accelerating growth further.
People move because of push factors in the countryside and pull factors in cities. Common push factors include rural poverty, mechanisation of farming reducing labour needs, drought or land degradation, and limited access to schools or hospitals. Pull factors include better-paid jobs in factories or services, brighter-lit streets and entertainment, the chance of a university education and access to clean water and electricity. The reality often falls short of the hope — many migrants end up in informal slums — but the contrast with rural conditions still makes the move worthwhile.
The world urban share rose from about 30% (1950) to roughly 57% (today) and is projected to hit 68% by 2050. Almost all future urban growth will happen in developing and emerging countries.
Different Speeds in Different Places
Not every country is urbanising at the same speed. Developed countries are already 80% or more urban; their growth is now slow or even slightly negative as people retire to the coast or countryside. Emerging countries like India and Brazil are urbanising fast as factories, services and infrastructure expand. Developing countries have the lowest urban share but the highest rates of urban growth. Africa is the most rural continent today but is urbanising the quickest — Lagos in Nigeria adds about 77 new residents every hour.
Cities also reshape themselves internally. Suburbanisation is the spread of housing outwards into the urban-rural fringe, common across the UK from the 1930s. Counter-urbanisation is people moving from cities to small towns or villages, which has happened in parts of southern England as remote working has spread. Re-urbanisation is the return of people to inner-city areas after regeneration — London Docklands, Manchester city centre and Liverpool waterfront are British examples. Most cities show all three processes happening at once in different neighbourhoods.
Megacities and Urban Primacy
A megacity has more than 10 million inhabitants. In 1950 there were only two: New York and Tokyo. By 2025 there are around 35, and the great majority are in Asia, Africa and Latin America. Tokyo (about 37 million) and Delhi (about 33 million) lead the league. Most growth in the next twenty years will come from cities like Lagos, Dhaka, Karachi and Kinshasa — cities most British students would struggle to place on a map.
In many countries one city stands far above the rest in size, wealth and political importance. Geographers call this urban primacy. Bangkok dwarfs every other Thai city. Lima houses about a third of all Peruvians. Lagos handles most of Nigeria’s formal economy. Primacy concentrates investment but also concentrates problems — traffic, pollution, slum housing — into a single overcrowded centre.
A megacity has over 10 million people. Numbers grew from 2 megacities (1950) to roughly 35 today, with most new megacities forming in Asia and Africa. Urban primacy is when one city dominates a country.
Formal vs Informal Economies
Cities in different parts of the world have different economies. The formal sector includes registered factories, offices and retail. The informal sector covers street trading, recycling, casual labour and home-based work. In developed countries the informal sector is small. In emerging cities like Mumbai or Lagos it employs over half the workforce. Conditions are often poor, with no contracts, sick pay or pensions, but the sector absorbs new arrivals who cannot find formal jobs immediately.
To find percentage change in urban population: subtract the start value from the end value, divide by the start value and multiply by 100. For example, Lagos grew from about 7.3 million in 2000 to 15.4 million in 2024. Change = 8.1 million; 8.1 / 7.3 = 1.11; × 100 = 111% growth in 24 years. Annual rate ≈ 111 / 24 ≈ 4.6% a year. Exam tip: always show your working. A clear method can still earn credit when the final figure is wrong.