Changing towns and cities

Where people live: global urban growth and why the rates vary

Urbanisation is the rise in the share of a country's population living in towns and cities. More than half of the world's people now live in urban areas, but the rate of change is very different from place to place, and the syllabus asks you to explain that variation rather than just describe it.

The first reason is how far a country has already urbanised. Many HICs urbanised during their industrial revolution, when factories, railways and port jobs pulled people off the land, so there is little rural population left to move and their urban growth is now very slow. Many LICs and MICs are urbanising now, and their rates are much faster because a large rural population is still moving, and because their cities are growing from a small base, so the same number of new arrivals is a much bigger percentage increase.

The second reason is the economy. Countries whose growth is driven by manufacturing, mining, tourism or services create city jobs quickly, and cities grow with them. Countries whose economies depend on farming grow more slowly in urban terms, because there is less reason to leave the land. The third reason is government policy: a state can direct growth towards particular cities through investment, new transport links or by moving its capital, and it can slow growth by restricting migration into a city, as China did with the household registration system.

Growth also concentrates within a country. The largest city usually pulls migrants from the whole country, not just its own region, because that is where the national jobs, universities, hospitals and government are, so it grows faster than the towns around it and the gap between the biggest city and the rest widens. That is why a country's urban growth rate and the growth rate of its capital can be two very different figures.

Causes of rapid urban growth in LICs

Rapid urban growth in an LIC has two engines, and a full answer uses both: rural to urban migration and natural increase in the city itself. Migration brings people in, and then those people have children, so the city keeps growing even after the flow of migrants slows.

Rural to urban migration is driven by push and pull factors. Push factors from the countryside include low farm incomes, a shortage of land as holdings are divided between sons, drought and crop failure, a lack of schools and clinics, and few jobs outside farming. Pull factors towards the city include the hope of paid work, higher wages, better schools and hospitals, electricity and clean water, and the idea that the city offers a better life, which is spread by television, social media and by relatives who have already moved.

The syllabus asks you to sort the causes into social, economic, environmental and political factors, and the same factor can be both a push and a pull depending on which end you are looking at.

• Economic: more paid jobs, higher wages and more trade in the city; low farm incomes and few jobs in the countryside.
• Social: schools, clinics, universities and entertainment in the city; poor services, limited education and isolation in the countryside; young adults also move because cities are where other young people are.
• Environmental: drought, soil erosion, flood and crop failure push people off the land; cities offer shelter, piped water and electricity, though the environment in a fast-growing city may itself be polluted and overcrowded.
• Political: government investment, new roads or a new capital attract growth, while conflict, insecure land tenure or forced resettlement push people towards the city; some governments also restrict movement into cities.
• Natural increase: a young migrant population of childbearing age has a high birth rate in the city, so the urban population grows from within as well as by migration.

The opportunities of urban living

Rapid urban growth is usually described as a problem, but the syllabus asks first about the opportunities, and they are the reason people move. The most obvious is economic development. Cities concentrate workers, markets, transport and services in one place, so businesses there are more productive than the same businesses scattered across the countryside. Wages are higher, there is more variety of work, and the money earned in the city is often sent back to relatives in the countryside as remittances.

Cities also provide services and housing that rural areas cannot support. A hospital with specialist staff, a university, a reliable electricity supply, piped water, a sewage system and a public transport network all need a large concentrated population to pay for them. Culture and leisure are part of the same picture: cinemas, theatres, sports clubs, restaurants, places of worship and markets for every community, all of which depend on having many people within reach.

Then there is consumption. People in cities buy more goods and services, which supports shops, factories, transport and finance, and that spending is what turns a city into a market that attracts further investment. This is why a city can be a country's engine of growth: a large share of national economic output may come from one or two urban areas, which is both an opportunity and a risk, because the rest of the country depends on them.

Finally, cities can offer social opportunity. Women in particular often find more paid work and more independence in a city than in a village, and children may have better access to education. A well-managed city spreads these benefits; a badly managed one concentrates them among the people who can afford to pay.

Housing, unplanned settlements and inequality

When a city grows faster than it can build, the first thing to fail is housing. New arrivals cannot afford formal housing, so they build for themselves on land that nobody else wanted: a steep slope, a floodplain, a rubbish tip or land beside a railway. These are unplanned settlements, also called informal settlements or shanty towns. They are usually built from whatever materials are available, they often have no legal right to the land, and they may lack piped water, sewers, paved roads, drainage and electricity. Because they are on marginal land, they are also the parts of the city most at risk from flooding, landslides and fire.

It matters where that housing sits, because the challenges are concentrated in particular parts of the city. Land that is well connected and close to work is the most expensive, so the poorest households are pushed onto the cheapest land, which is usually the land nobody else wanted: steep slopes, floodplains, ground beside railways or industry, or the far edge of the city where services and transport arrive last. So the poorest housing and the worst services tend to end up in the same places, and the people living there are the ones most exposed to flooding, landslides and fire.

Inequality is the other side of the same problem. A fast-growing city usually contains great wealth and great poverty within a short distance of each other: a business district with offices and hotels, and an unplanned settlement with no sewerage a few streets away. Inequality matters because it decides who has clean water, who has a school place, who can reach a clinic and who lives on land that floods. It also affects how the city is governed, because people who have no legal title to their land and no formal address have little influence over the decisions that affect them.

It is worth judging the opportunities and the challenges together. Rapid growth does raise incomes, create jobs and pay for better services in the long run, but only where the city can build infrastructure fast enough. Where it cannot, the same growth produces unplanned settlements, congestion and disease, and the benefits stay with the people who were already better off.

Services, employment, transport and waste management

Service provision is a race the city usually loses for a while. Water, sewerage, electricity, schools, clinics and refuse collection all have to be extended to new districts that appear faster than the pipes and the staffing can be planned. The result is that services are uneven: a formal suburb gets them, and an unplanned settlement next door does not, even though the people there pay for them indirectly through the prices they pay for water bought from tankers or vendors.

Employment is mixed. Cities create jobs, but not always enough formal jobs for the number of people arriving, so a large part of the workforce ends up in the informal sector: street trading, waste collection, repairs, domestic work, transport and construction, with no contract, no pension and no security. The informal sector is not useless. It keeps families alive and it provides cheap services that the city itself does not, but workers in it are vulnerable, they pay no tax, and the government has no reliable record of them, which makes planning harder.

Transport breaks down in the same way. Roads built for a much smaller city cannot carry the traffic of a city that has doubled, and public transport may be informal minibuses rather than a planned network. The consequences are long journeys to work, lost working hours, air pollution and accidents. The people who suffer most are those in unplanned settlements on the edge of the city, who are furthest from the jobs and cannot afford the fare.

Waste management fails last and is noticed most. When a city grows faster than its collection service, rubbish is dumped in streets, drains and open ground or burned. Blocked drains then make flooding worse, and standing water and rubbish together spread disease. In many cities a large part of the recycling that does happen is done by informal waste pickers, who earn a living from material the official system never collects, which is a reminder that informal work is doing real work for the city.

Urban sprawl and the rural-urban fringe

Urban sprawl is the outward spread of a city into the surrounding countryside, usually as low-density housing, business parks, superstores and roads. It happens when land in the city centre is too expensive or too crowded, when people want larger homes with gardens, and when the road network makes it possible to live further out and still reach work. The zone where the city meets the countryside is the rural-urban fringe, and it is the place where the impact is felt first.

Impacts on the surrounding area. Farmland is built over, and it is usually the best farmland, because cities grew up on flat, fertile, well-drained lowland in the first place. Villages at the edge of the city grow into suburbs and lose their separate identity, and local services change: village shops close as superstores open, and schools and roads are overwhelmed. Commuter traffic increases, and journeys into the city become slower for everyone. Air, noise and light pollution spread outwards, and drainage changes as fields are covered with roofs, tarmac and drains, so rainfall reaches the river faster and the risk of flooding rises downstream.

Impacts on the city and its people. Sprawl can bring benefits as well as costs. Housing is cheaper and larger on the fringe, there is more space for schools, hospitals and parks, and business parks create jobs outside the crowded centre. It also relieves pressure on the inner city. But it increases car dependence, which raises emissions, and it can leave the inner city with a declining population and a shrinking tax base while the new suburbs need new infrastructure. Sprawl also consumes land permanently: once good farmland is built on, it cannot easily be returned to food production.

This is why many cities try to control sprawl rather than simply accommodate it. Green belts, growth boundaries and protected farmland limit how far the city can spread; compact high-density development, brownfield redevelopment and improved public transport aim to fit more people into less land. Whether those strategies work is an evaluation question, and the answer depends on whether enough housing is built inside the boundary to keep prices down.

Managing urban growth: strategies, techniques and sustainability

Management of urban growth works on two fronts: improving the places people already live, and planning where the city will grow next. The syllabus asks you to evaluate both, including how sustainable they are, so every strategy you name needs a strength and a limitation.

Upgrading unplanned settlements is the most direct approach. Self-help schemes give residents secure land title, a loan and materials so they improve their own homes, and sites-and-services schemes provide a plot with water, drainage, electricity and a road, and let people build the house themselves. Both are far cheaper than clearing a settlement and rehousing everyone, and both keep people near their work and their community. The limitations are real: upgrading takes years, it works only where the land is safe from flooding and landslides, and giving people title can raise land values so that the poorest tenants are pushed out anyway.

Housing programmes work at a larger scale. Building new towns and satellite settlements moves growth away from the crowded core; mass public housing, as Singapore's Housing and Development Board has provided, gives secure homes at a price people can pay; and redeveloping the inner city puts people back on land that already has roads, pipes and schools. The limitation is cost and pace: governments can rarely build fast enough to match the arrivals, and relocation to a distant new town can leave residents far from work.

Transport strategies aim to move more people in less road space. Bus rapid transit, as developed in Curitiba in Brazil, gives buses their own lanes, stations and priority at junctions, so a high-capacity service can be built for far less than a metro. Rail, cycle lanes, park-and-ride and restrictions on cars in the centre all help, and each reduces congestion, air pollution and the time lost in travel. The limitations are the cost of building and maintaining the network, the need for it to reach the unplanned settlements rather than only the formal districts, and the fact that a new road or rail line can raise land values and push poorer residents outwards.

Services, waste and the environment need managing too. Extending water, sewerage and electricity into unplanned settlements cuts disease immediately; organised refuse collection, recycling and composting reduce the rubbish that blocks drains and causes flooding; and protecting parks, floodplains and open land keeps the city cooler and safer. Curitiba again shows the principle: land beside rivers was left as parkland that floods harmlessly instead of being built on, which reduced flood damage and provided green space at the same time.

Planning and dispersal operate at national scale. Master plans and zoning decide what may be built where; green belts and growth boundaries limit sprawl; and some countries move growth away from the largest city altogether. Indonesia is building a new capital, Nusantara, on the island of Borneo to relieve the pressure on Jakarta. The limitation of dispersal is cost and time: new capitals and new towns are enormously expensive, and they may simply create a second growing city rather than reducing the growth of the first.

Evaluate sustainability by asking three questions. Does the strategy meet present needs, in housing, water, sanitation, transport and employment? Does it do so without damaging the environment, for example by protecting farmland, floodplains and air quality? And will it keep working in the future, with a funding and maintenance plan, secure land rights, and jobs nearby rather than housing in a place with no work? A strategy that answers yes to all three, such as upgrading a settlement on safe land with piped water and a bus route to the city, is more sustainable than a prestige project that only a minority can afford.

• Upgrading: self-help schemes and sites-and-services schemes, with secure land title. Strength: cheap, keeps communities and jobs. Limitation: slow, needs safe land, can raise rents and displace tenants.
• Housing: new towns, satellite settlements, mass public housing, inner-city redevelopment. Strength: adds supply at scale. Limitation: expensive, and slow to match the rate of arrivals.
• Transport: bus rapid transit, metro and rail, cycle lanes, car restrictions, park-and-ride. Strength: moves more people in less space and cuts pollution. Limitation: costly, and must reach the poorest districts to be fair.
• Services and environment: piped water, sewerage, refuse collection, recycling, protected floodplains and green space. Strength: immediate health and flood benefits. Limitation: needs continuing funding and maintenance.
• Planning and dispersal: master plans, zoning, green belts and growth boundaries, new capitals and new towns. Strength: controls where growth happens. Limitation: expensive and slow, and may not reduce growth in the original city.