IB Geography • Section G2
Changing Urban Systems
How economic and demographic processes bring change over time to urban systems
Restored from the original AdornGeo Weebly page • syllabus order preserved
Urbanisation, Natural Increase and Urban Growth
Urbanization, natural increase and centripetal population movements, including rural–urban migration in industrializing cities, and inner-city gentrification in post-industrial cities.
The original AdornGeo sequence begins by separating urbanisation (a rising proportion of people living in towns and cities) from urban growth (a rising urban population). Students then use the page's migration-or-natural-increase enquiry to explain why the balance between the two processes varies between cities and over time.
- Urbanisation is a proportional change; urban growth is a change in the number of urban residents.
- Natural increase occurs when births exceed deaths and is often important where a city has a youthful age structure.
- Migration changes both city size and composition, while reclassification can change the statistical urban boundary.
- The fastest rates of urban growth are not necessarily found in the world's most urbanised countries.
Migration or natural increase?
- Define urbanisation and urban growth, then write one example that demonstrates the difference.
- Use UN data to compare the urban share and urban growth of one industrialising and one post-industrial country.
- Watch the original page's natural-change theme, then draw a two-process model showing how migration and natural increase interact.
- Explain why a city can grow while the national rate of urbanisation slows.
Watch: Why are people moving to cities?
Centripetal Population Movements
Centripetal population movements, including rural–urban migration in industrializing cities and inner-city gentrification in post-industrial cities.
Centripetal means movement towards the urban centre. The recovered page teaches two sharply contrasting versions: China's enormous rural–urban flow, driven by uneven opportunity and shaped by the hukou system, and gentrification, where investment and higher-income residents return to post-industrial inner-city neighbourhoods.
- Rural push and urban pull factors operate together, but migrant networks, state policy and transport affect who can move.
- China's hukou registration system can separate physical residence from full access to urban public services.
- Gentrification brings reinvestment, renovation and a larger tax base but can also raise rents and displace residents and businesses.
- Re-urbanisation describes renewed population and investment in the city; gentrification is one selective and contested form of it.
Two inward movements, two sets of winners
- Use the China activity to classify migration causes as economic, social, demographic, political or environmental.
- Create a stakeholder table for migrants, rural families, employers and city government; include one benefit and one cost for each.
- Read the original gentrification document and construct a six-stage neighbourhood-change sequence.
- Compare the two movements: who moves, why, towards which part of the urban system, and with what consequences?
Watch: Urban migration for young Chinese
Watch: China in transition: rural–urban migration
Watch: China's urban billion
Centrifugal Population Movements
Centrifugal population movements, including suburbanization and counter-urbanization.
Centrifugal movements carry people and activity away from the urban core. The lesson distinguishes suburbanisation within the built-up area from counter-urbanisation beyond it, and links both to transport, land prices, housing preferences, employment change and the urban life cycle.
- Suburbanisation expands residential and economic activity towards the edge of a city and is often associated with urban sprawl.
- Counter-urbanisation moves people from large cities to smaller settlements and rural areas beyond the commuter belt.
- Road building, private car ownership, remote work and decentralised employment can weaken the friction of distance.
- Outward movement can redistribute congestion, service demand, inequality and environmental pressure rather than remove them.
Map the outward city
- Draw an urban transect from CBD to rural hinterland and locate suburbanisation, urban sprawl and counter-urbanisation.
- Create a cause-and-consequence chain linking transport change, land price, housing demand and outward movement.
- Use satellite imagery to compare the edge of a compact city with a sprawling city; annotate road pattern, density and green-space loss.
- Judge whether centrifugal movement is best understood as a choice, a market outcome or a planning decision.
Watch: Urban change and the outward city
Urban System Growth and Infrastructure
Urban system growth including infrastructure improvements over time, such as transport, sanitation, water, waste disposal and telecommunications. Case study of infrastructure growth over time in one city.
As an urban system grows, infrastructure must connect a larger and more complex set of homes, workplaces and services. Shanghai provides the located synthesis: rapid demographic and economic growth has been accompanied by expansion of metro, road, water, sanitation, waste and digital networks, while provision and access remain uneven.
- Infrastructure both responds to urban growth and enables further growth by changing accessibility and carrying capacity.
- Network expansion is spatially selective; city averages can hide differences in reliability, affordability and access.
- Large transport projects restructure land values, commuting flows and the location of new housing and employment.
- A strong case study shows change over time and evaluates capacity, coverage, environmental effects and equity.
Shanghai infrastructure timeline
- Use the original Shanghai handout to establish the city's location, growth phases and changing global functions.
- Build a dated timeline for metro, water, sanitation, waste and telecommunications; add evidence of scale to each strand.
- Annotate a map to show how infrastructure has connected Pudong, Puxi, new towns, ports and airports.
- Evaluate which infrastructure improvement has had the greatest multiplier effect and identify one group or district that benefits less.
Watch: The story of Shanghai, China's largest city
Watch: Shanghai urban growth, 2001–2019
Watch: Shanghai: Better city, better life?
Shanghai: infrastructure growth over time
Shanghai's transformation from river-port and industrial city to a vast global metropolis makes visible the two-way relationship between infrastructure and urban growth.
- Transport: the metro network, bridges, tunnels, expressways, ports and airports reshape accessibility.
- Water and sanitation: expanding supply and treatment must keep pace with population and industrial demand.
- Waste: a larger material throughput creates collection, landfill, incineration and recycling challenges.
- Telecommunications: digital infrastructure strengthens Shanghai's service economy and global connectivity.
Urban Deindustrialisation — Detroit
The causes of urban deindustrialization and its economic, social and demographic consequences.
The recovered AdornGeo page concludes with Detroit. Its original note-taking activity, presentation, wiki and interactive ask students to connect factory closure to a chain of job loss, tax-base decline, out-migration, segregation, vacant land and service pressure—while also considering selective reinvestment and competing narratives of recovery.
- Deindustrialisation is a long-term decline in manufacturing employment and activity, not simply the closure of one factory.
- Automation, global competition, relocation, changing transport and corporate decisions combine across scales.
- Multiplier effects spread job loss into retail, housing, public finance, schools, infrastructure and population change.
- Consequences are socially and spatially uneven; race, class, mobility and political power shape who can leave and who absorbs the costs.
Detroit: from Motor City to a contested recovery
- Complete the original deindustrialisation note-taking framework using causes at local, national and global scales.
- Build a systems diagram beginning with automobile-industry restructuring and ending with economic, social and demographic consequences.
- Use before-and-after maps or imagery to locate population loss, vacancy and reinvestment rather than describing Detroit as uniformly declining.
- Evaluate the claim that recent downtown investment represents recovery for the whole city. Use stakeholders and spatial evidence.
IB synthesis and exam practice
- Create a two-column comparison of centripetal and centrifugal changes across China, Shanghai and Detroit.
- Add a feedback arrow showing how demographic change can alter infrastructure, employment and further migration.
- Answer: Examine how economic and demographic processes have changed one urban system over time.
Watch: Detroit's rise, decline and reinvention
Watch: Understanding Detroit's urban change