The big idea: A megacity is a city with 10 million or more inhabitants.
The number of megacities has grown fast — most new ones are in Asia and Africa, where cities are growing very quickly. Rapid growth brings both problems and benefits.
Key terms
- Megacity — an urban area with a population of 10 million or more.
- Rapid urban growth — a city's population rising quickly, from migration and natural increase.
- Urbanisation — the rising share of people who live in towns and cities.
- Informal settlement — unplanned, often self-built housing (a slum) that grows when a city expands faster than it can house people.
Where megacities are: Most of today's megacities are in lower- and middle-income countries.
By 2030 the countries forecast to hold the most megacities are China and India — both have huge, fast-growing urban populations.
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Rapid megacity growth has two sides. A good answer can give drawbacks and benefits, and say who feels each — an individual (one resident) or wider society (the whole city or country).
| Drawbacks (problems) | Benefits (opportunities) |
|---|---|
| Housing shortages and informal settlements (slums) | More jobs and higher wages than in rural areas |
| Traffic congestion and air pollution | Better access to schools, hospitals and services |
| Pressure on water, sanitation and electricity | Economic growth — megacities drive national GDP |
| Unemployment and inequality | Easier to provide services to people who are close together |
How this is tested: Paper 2 Q1/Q5 asks you to Explain two downsides of fast growth, or two benefits — usually [4 marks], 2 per developed point.
Explain two likely problems for a city expected to grow very quickly.
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Two scales of benefit: Megacity growth can help individuals (one person) and wider society (the whole city or country):
- An individual gains a job, higher pay or access to a hospital or university. - Society gains because megacities create wealth, drive national GDP and make services cheaper to provide to people living close together.
Ways an individual benefits
- Better-paid work — far more, and higher-paid, jobs than in the countryside.
- Services nearby — schools, hospitals and universities within reach.
- Choice and opportunity — shops, culture and the chance to start a business.
Explain two ways an individual can benefit socially or economically from megacity growth.
Model answer plan
See the mark-by-mark plan — for / against / judgement, with marking guidance — in study mode.
Name the scale: When a question contrasts individual vs society, say which scale your point sits at — examiners reward answers that clearly separate the two.
How this is tested: A line graph of megacity populations over time (or a megacities infographic) is the usual stimulus here, so the first marks are pure figure-reading.
Expect to Estimate a population from the axis [1], Identify the fastest-growing city [1], Determine a value such as a range [1], then Describe the overall pattern [2]. Read the key first and always quote the units.
Read the key first. Which line is highest, and which one rises most steeply?
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Using the graph, estimate Delhi's population in 2020 and identify the megacity that grew fastest.
Model answer plan
See the mark-by-mark plan — for / against / judgement, with marking guidance — in study mode.
| Megacity | 2000 | 2020 |
|---|---|---|
| Tokyo | 34 | 37 |
| Delhi | 16 | 31 |
| Shanghai | 14 | 27 |
| Lagos | 7 | 14 |
| Mumbai | 16 | 20 |
IB-style question — read the figure
Using the table above: (a) estimate the population of Delhi in 2020 [1]; (b) identify which megacity grew fastest between 2000 and 2020 [1]; (c) describe the overall pattern of growth shown [2].
How to answer each part
- (a) Estimate Delhi 2020. Read Delhi's 2020 column -> about 31 million. Always give the unit.
- (b) Identify the fastest-growing. Compare the rise for each city. Delhi rose from 16 to 31 (+15m) and Lagos doubled (7 to 14, +7m) — Delhi gained the most people, so Delhi grew fastest by size.
- (c) Describe the pattern. Almost every city grew, but the Asian and African cities (Delhi, Shanghai, Lagos) grew fastest, while Tokyo barely changed (34 to 37) — it is already large and in a high-income country.
Final answer
(a) ~31 million; (b) Delhi (largest gain, +15m); (c) most grew, fastest in Asia/Africa, slowest in Tokyo.
Identify vs Estimate vs Determine: Identify = read a value/label straight off. Estimate = a sensible figure from the axis. Determine = work out a value (e.g. a range = highest minus lowest).