Urban Growth, Hierarchy and Primate Cities (Cambridge IGCSE/A‑Level Geography 9696)
Learning Objective
Explain the causes and consequences of primate cities, analyse how they fit within wider urban‑growth processes, and evaluate strategies that aim to create a more balanced and sustainable urban system.
1. Urban‑Growth Processes & Causes (Syllabus 6.1.1‑6.1.3)
Urban growth is driven by a combination of demographic, economic and policy factors. Understanding these processes provides the context for primate‑city development.
- Urbanisation (core process) – net migration from rural to urban areas plus natural increase within cities. This creates the demographic base for any large city.
- Sub‑urbanisation – outward expansion of low‑density housing on the urban fringe, often linked to cheaper land, desire for larger homes and improved transport.
- Counter‑urbanisation (de‑urbanisation) – migration from cities to rural or semi‑rural areas, usually motivated by lifestyle, remote‑working or retirement.
- Re‑urbanisation (urban regeneration) – renewal of inner‑city areas through investment, gentrification, brownfield redevelopment or cultural regeneration.
1.1 Population vs. Area Growth
Urban growth can be expressed as:
- Population growth rate – % change in urban population per year.
- Built‑up area growth rate – % change in the spatial extent of urban land (satellite‑derived built‑up area).
| Country (2023) |
Urban‑population share (%) |
Annual urban‑population growth |
Annual built‑up‑area growth* |
| Uganda (low‑income) |
24 |
+3.5 % |
+5.2 % |
| India (middle‑income) |
35 |
+2.3 % |
+3.0 % |
| United Kingdom (high‑income) |
84 |
+0.8 % |
+0.9 % |
*Built‑up‑area data from the Global Human Settlement Layer (GHSL, 2023).
1.2 Urban‑Sprawl vs. Compact Growth
- Urban sprawl – low‑density, dispersed development that expands the city’s footprint faster than population growth, often leading to higher transport demand and loss of peri‑urban farmland.
- Compact growth – higher density, mixed‑use development within existing urban boundaries, encouraging public transport use, reducing per‑capita infrastructure costs and limiting land‑use pressure.
Both patterns can coexist in a primate city: the CBD and inner districts tend to be compact, while the outer fringe often experiences sprawl.
2. Urban Hierarchy: Primate vs. Balanced (Polycentric) Systems (Syllabus 6.2.1‑6.2.3)
2.1 What is a Primate City?
- Largest city in the country and at least twice the size (population) of the second‑largest city.
- Concentrates the majority of national economic, political and cultural functions (finance, industry, government, media, higher education).
- Forms the core of a core‑periphery system, generating strong spatial inequality.
2.2 Balanced (Polycentric) Urban System
- Several cities of comparable size and function.
- Economic activity, services and infrastructure are more evenly distributed.
- Reduces regional disparity, spreads risk of economic shocks and can limit urban‑sprawl.
2.3 Sketch of Horizontal vs. Vertical Structure
A typical primate city shows:
- Horizontal expansion – low‑rise suburbs and peri‑urban fringe (sprawl).
- Vertical development – high‑rise CBD, mixed‑use towers and high‑density residential blocks (compact core).
In a balanced system the horizontal pattern is repeated around several medium‑size cores, with less extreme verticalisation.
3. Causes of Primate‑City Development (Syllabus 6.3.1‑6.3.3)
- Historical centralisation – colonial capitals or early nation‑state seats become entrenched administrative and commercial hubs (e.g., Nairobi, Manila).
- Agglomeration economies – reduced transport costs, larger markets, knowledge spill‑overs and specialised labour pools attract firms and workers.
- Infrastructure bias – major roads, ports, airports and telecommunication networks are concentrated in the main city, reinforcing its dominance.
- Rural‑to‑urban migration pull – jobs, education, health services and perceived higher living standards draw people to the primate city.
- Policy focus – deliberate investment in the capital (e.g., special economic zones, “growth poles”) to “jump‑start” national development.
- Scale of governance – centralised decision‑making privileges the capital, marginalising regional voices.
- Geographic advantage – location on a river, coast or at a transport crossroads can give the city a natural comparative edge.
4. Consequences of Primate Cities
4.1 Economic Consequences
- High contribution to national GDP (often >30 %).
- Regional disparity – peripheral regions receive less investment, suffer higher unemployment and lower income levels.
- Economic vulnerability – shocks (natural disasters, financial crises) affect the whole national economy.
4.2 Social Consequences
- Housing pressure → informal settlements, slums, unaffordable rents.
- Service inequality – better health, education and cultural facilities in the primate city.
- Brain drain from smaller towns; demographic imbalance (ageing peripheries, youthful city).
- Increased social segregation (by income, ethnicity, migrant status).
4.3 Political Consequences
- Centralised decision‑making can marginalise regional interests, fuelling calls for de‑centralisation or autonomy.
- Potential for regional tensions and uneven political representation.
4.4 Spatial & Environmental Consequences
- Urban sprawl → loss of peri‑urban farmland, wetlands and natural habitats.
- Transport congestion, higher air‑pollution and greenhouse‑gas emissions.
- Imbalanced land‑use patterns – “core‑periphery” model.
- Pressure on water resources, solid‑waste management and energy supply.
- Urban heat‑island effect intensified by loss of vegetation.
5. Urban Structure & Land‑Use Zones (Syllabus 6.2.2)
The internal layout of a primate city sustains its dominance.
| Zone |
Typical Functions |
Key Drivers |
| Central Business District (CBD) |
High‑rise offices, finance, major retailers, main transport hub |
Agglomeration economies, land‑value maximisation, historic centrality |
| Secondary Commercial/Service Districts |
Shopping malls, hotels, entertainment, specialised services |
Decentralisation of retail, rise of auto‑oriented development |
| Industrial Zones |
Manufacturing, logistics, warehousing, often near ports or highways |
Transport accessibility, land‑cost considerations, zoning policy |
| Residential Zones |
- High‑density inner‑city apartments
- Mid‑density suburban estates
- Low‑density peri‑urban housing (formal & informal)
|
Income levels, ethnicity/migrant status, planning regulations, availability of land |
| Green Spaces & Public Amenities |
Parks, riverfronts, cultural institutions, sports facilities |
Municipal policy, historic preservation, demand for recreation |
| Vertical Growth |
Skyscrapers, high‑rise residential blocks, mixed‑use towers |
Land scarcity, high land values, modern zoning that permits high‑rise |
5.1 Residential Zonation Drivers
- Income – high‑income groups occupy central or high‑rise apartments; low‑income groups live in outer suburbs or informal settlements.
- Ethnicity / Migration status – ethnic enclaves or migrant quarters often form in specific districts (e.g., Chinatown, migrant worker camps).
- Planning & policy – zoning ordinances, affordable‑housing mandates, land‑readiness schemes.
- Accessibility – proximity to public transport, employment centres, schools.
5.2 Place‑Identity
Place‑identity refers to the symbolic and emotional meanings attached to particular urban areas (e.g., historic districts, cultural precincts). In a primate city, iconic landmarks (e.g., the Eiffel Tower in Paris) reinforce the city’s national identity and attract tourism, further strengthening its primacy.
6. Sustainable Urban Development in Primate Cities (Syllabus 6.3.1‑6.3.3)
Key sustainability challenges and illustrative examples of how some cities are tackling them.
| Issue |
Typical Challenge in Primate Cities |
Illustrative Example & Evaluation |
| Solid‑waste management |
Rapid population growth overwhelms collection and disposal; reliance on landfills. |
Singapore – Waste‑to‑Energy (WTE)
• 95 % of municipal waste incinerated, electricity generated.
• Success: Reduces landfill demand, provides renewable energy.
• Limitations: High capital cost, requires sophisticated technology and public acceptance. |
| Transport congestion |
Road networks centred on the CBD become saturated; air quality deteriorates. |
Curitiba (Brazil) – Bus Rapid Transit (BRT)
• Dedicated lanes, high‑frequency buses, integrated ticketing.
• Success: Shifted ~70 % of commuters from cars, cut emissions.
• Limitations: Effectiveness falls where private car ownership is very high; needs strong governance. |
| Housing affordability |
Informal settlements proliferate; formal housing supply lags behind demand. |
Vienna (Austria) – Social‑housing model
• 60 % of residents live in municipally owned or subsidised apartments.
• Success: Low rent, high quality, social integration.
• Limitations: Requires long‑term political commitment and substantial public funding. |
| Green space & urban heat‑island |
Loss of vegetation raises temperatures and degrades air quality. |
Seoul (South Korea) – Cheonggyecheon Restoration
• Removed elevated highway, restored 8 km river corridor with parks.
• Success: Improved micro‑climate, increased biodiversity, boosted tourism.
• Limitations: High upfront cost; benefits concentrated near the centre. |
7. Management Strategies & Evaluation (AO3)
Policies aim to reduce the dominance of the primate city and promote a more balanced, sustainable urban system.
- Decentralisation of government and institutions
- Relocating ministries, universities and research centres to secondary cities.
- Evaluation: Stimulates regional economies and eases migration pressure, but success depends on adequate infrastructure, incentives and political will.
- Investment in secondary‑city infrastructure
- High‑speed rail, secondary airports, ports, digital connectivity.
- Evaluation: Improves accessibility and attracts business; returns are often slow and can be undermined by continued capital bias toward the capital.
- Special Economic Zones (SEZs) and industrial parks outside the primate city
- Tax breaks, streamlined regulations, export‑oriented facilities.
- Evaluation: Generates jobs and diversifies the economy; risk of creating enclaves with limited linkages to the wider region.
- Urban‑rural integration policies
- Improving rural health, education, internet and transport to curb push factors.
- Evaluation: Tackles root causes of migration; requires long‑term funding and inter‑ministerial coordination.
- Balanced regional planning
- Coordinated land‑use, housing, transport and environmental strategies across the whole urban system.
- Evaluation: Promotes sustainable growth and reduces sprawl; effectiveness hinges on strong governance, stakeholder participation and clear monitoring.
8. Comparative Table: Primate‑City System vs. Balanced (Polycentric) System
| Aspect |
Primate‑City System |
Balanced (Polycentric) System |
| Population distribution |
One city dominates (> 2 × second‑largest) |
Several cities of comparable size |
| Economic activity |
Concentrated in the primate city |
Spread across regional centres |
| Infrastructure investment |
Heavy bias to the capital |
More even distribution |
| Regional development |
Peripheral lag, high inequality |
Balanced growth, lower inequality |
| Vulnerability to shocks |
High – single‑city dependence |
Lower – diversified urban base |
| Environmental pressure |
Intense (pollution, waste, sprawl) |
More manageable; opportunities for green infrastructure |
9. Detailed Case Study: Bangkok, Thailand (Primate City)
Why Bangkok qualifies as a primate city
- Population ≈ 10 million (≈ 55 % of Thailand’s total).
- Contributes ~30 % of national GDP; hub for finance, manufacturing, tourism and services.
- Seat of government, major universities, national media and cultural institutions.
Key Consequences
- Economic: Rapid growth attracted foreign investment, yet provinces lag in job creation and income.
- Social: Large informal settlements along the Chao Phraya River; housing affordability crisis drives household crowding.
- Political: Centralised decision‑making has sparked regional calls for de‑volution of authority.
- Spatial/Environmental: Chronic traffic congestion (average speed < 15 km h⁻¹), air‑quality frequently exceeds WHO limits, frequent flooding caused by loss of wetlands and extensive impervious surfaces.
Management Strategies Implemented (2020‑2024)
- Mass Rapid Transit (MRT & BTS) – expanded rail network to ≈ 200 km. Evaluation: Reduced car trips by ~12 % in served corridors; high capital cost and still limited coverage of outer districts.
- Bangkok Green Belt Plan – earmarks 30 % of surrounding land for agriculture and parks. Evaluation: Slows sprawl, but enforcement weak against illegal high‑rise development.
- Waste‑to‑Energy Plant (Bangkok Eco‑Power) – incinerates 4 Mt of municipal waste/yr, generates 150 MW electricity. Evaluation: Cuts landfill use, but public concerns over emissions and health impacts persist.
- Partial decentralisation of ministries – relocation of several ministries to Nonthaburi and Pathum Thani (sub‑urban provinces). Evaluation: Created jobs in the periphery, yet most high‑level decision‑making remains centred in the CBD.
Overall Assessment
Bangkok’s interventions have mitigated some negative impacts (traffic, waste, sprawl) but the city remains overwhelmingly dominant. Sustainable balance will require stronger regional investment, stricter enforcement of green‑belt policies, and a continued focus on affordable housing beyond the city core.
10. Summary – Key Points for Exam Answers
- Primate cities develop through historical centralisation, agglomeration economies, infrastructure bias, migration pull and policy focus.
- They dominate the urban hierarchy, leading to economic concentration, social inequality, political centralisation and environmental stress.
- Urban‑growth typologies (urbanisation, sub‑urbanisation, counter‑urbanisation, re‑urbanisation) interact with primate‑city dynamics and must be considered in any analysis.
- Urban structure (CBD, secondary districts, residential zones, industrial zones, green space) and the balance between horizontal sprawl and vertical compact growth explain how dominance is maintained.
- Sustainable‑development challenges – waste, transport, housing, green space – can be tackled through BRT, waste‑to‑energy, social‑housing, river‑restoration, etc.; each solution has strengths and limitations.
- Effective management combines decentralisation, secondary‑city infrastructure, SEZs, urban‑rural integration and balanced regional planning, evaluated against equity, economic resilience and environmental impact.
- Case studies (Bangkok, Singapore, Curitiba, Vienna, Seoul) provide concrete examples of both the problems created by primate cities and the range of policy responses.