IB Geography HL — Changing urban systems

Key Idea: Topic 13.2 is about how urban systems change over time — how cities first explode in size, and then reshape themselves as industry leaves and people move out and back in. It pulls together two ideas: 13.2.1 — urbanisation, megacities & urban growth: the rising share of people in cities (urbanisation) and the rising number in any one city (urban growth), driven by natural increase + rural-urban migration — fastest in Africa and Asia (Lagos, Kinshasa), and the management challenges rapid growth creates. 13.2.2 — deindustrialisation, gentrification & urban change: how manufacturing decline triggers centrifugal outward movement (suburbanisation, counter-urbanisation), then a centripetal bounce-back (re-urbanisation, gentrification) — with winners and losers at every stage. This is an Option G topic, examined on Paper 1. SL answers 2 options, HL answers 3 (same questions). Expect short data-response reads off an urban-growth graph, a cluster of structured parts (State, Estimate, Suggest, Outline, Describe, Explain), and a [10] markband essay (Examine / To what extent).

🏙️ 13.2.1 — Urbanisation, megacities & urban growth

Urbanisation is the rising proportion of people living in towns and cities; urban growth is the rising number of people in a city — a country can be fully urbanised and still see its cities grow. A megacity has over 10 million people (Tokyo, Lagos, Mumbai). Cities grow from two engines at once: natural increase (a youthful migrant population with high birth rates) and rural-urban migration (push and pull factors). The skill examiners test is reading a line graph or table of urban share rising over time — State / Estimate / Identify a value with its units (% urban) — then Suggest or Explain causes, matched to the type (demographic, economic or social) the command asks for.

Not every city keeps booming. Tokyo, the world's largest, is now barely growing — Japan's birth rate is very low and rural-urban migration has run its course. Across Europe and North America, urbanisation is near its ceiling (75-85%), so the share rises slowly. Growth slows when birth rates fall, the rural population to draw on runs out, or people move back out (counter-urbanisation). On a question asking for ONE cause type (social / economic / demographic), a cause of another type scores zero.

🔄 13.2.2 — Deindustrialisation, gentrification & urban change

Deindustrialisation is the decline of manufacturing industry — factories close, jobs vanish, land falls derelict. It sets off a chain of urban change: people and money first move outwards (centrifugal — suburbanisation, then counter-urbanisation), hollowing out the inner city; later they move back in (centripetal — re-urbanisation and gentrification) as wealthier residents and investment return. The examiner skill is reading a falling-employment line graph (Describe the trend), then Explaining why manufacturing declines (marked 3 + 3 with a named city), and tracking both directions of movement plus the winners and losers they create.

Important: The benefits of urban change are uneven. Winners: incoming wealthier residents and developers (renovated housing, rising values) and the city (a higher tax base, restored buildings, new shops and culture). Losers: long-standing low-income residents priced out by rising rents, and local shops replaced by upmarket ones. Regeneration on paper can mean displacement for the original community — so an essay must weigh both sides and name a city (Detroit, Manchester, London, Barcelona).

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