The concept of a hierarchy of urban areas in a country

Urban Growth and the Hierarchy of Urban Areas

Learning objectives

By the end of the lesson students will be able to:

• Explain the main processes of urban growth, their causes and typical consequences (cause‑and‑effect).
• Define “urban hierarchy” and describe the functional hierarchy (primary → quaternary).
• Identify the different types of national urban systems – primate, poly‑centric and dual‑city – and give appropriate examples.
• Analyse the factors that determine a city’s rank in the national hierarchy, linking each factor to scale, place and change over time.
• Describe the typical horizontal and vertical structure of a city, the forces that cause change, and the sustainability challenges that arise.
• Apply the concepts to a contemporary case study, using quantitative data to evaluate economic, social‑equity and environmental outcomes.
• Use the knowledge to answer exam‑style questions with clear, structured arguments.

Key concepts

• Urban hierarchy – the ranking of towns and cities within a country according to population size, range of services and economic influence.
• Functional hierarchy – classification of urban centres by the complexity of functions they provide (primary, secondary, tertiary, quaternary).
• Primate (primate) city – a city that is at least twice as large as the next biggest city and dominates the national urban system.
• Poly‑centric system – a network of several cities of comparable size and importance.
• Dual‑city system – two major cities share national functions (e.g., political vs. economic); examples: Sydney/Melbourne (Australia), Abuja/Kaduna (Nigeria).
• Sustainable urban development – meeting present urban needs while minimising long‑term environmental, social and economic impacts.
• Scale, place, change over time, cause‑and‑effect, systems, diversity/equality – geographic concepts that underpin every part of the syllabus and should be highlighted in answers.

1. Urban growth – processes, causes and consequences

Urban growth is not a single phenomenon; several processes can operate simultaneously. The table distinguishes each process, notes the main drivers, and outlines typical outcomes.

2. Urban hierarchy – definition and functional basis

Urban hierarchy is the ordered ranking of settlements from the smallest rural service centre to the largest global city, based on two inter‑linked criteria:

1. Population size and density (scale).
2. Range and complexity of services (functional hierarchy).

The functional hierarchy reflects the sophistication of the services a centre provides:

• Primary services – basic retail, primary schools, GP surgeries.
• Secondary services – larger shops, secondary schools, district hospitals.
• Tertiary services – universities, specialised hospitals, professional services.
• Quaternary services – research institutes, multinational headquarters, major financial markets.

Higher‑ranked cities host a greater proportion of tertiary and quaternary functions, creating a flow of people, goods and information from lower‑ranked towns upward and a back‑flow of resources (e.g., commuting income) downward.

3. Typical levels in a national urban hierarchy (illustrative UK data, 2023)

4. Factors that determine a city’s rank in the hierarchy

• Population size and density – larger, denser populations can sustain more specialised services.
• Range and complexity of services (functional hierarchy) – presence of tertiary/quaternary functions pushes a city upward.
• Economic base – high‑value or knowledge‑intensive industries (finance, research) attract skilled workers.
• Transport and communication connectivity – airports, ports, rail hubs and digital networks reduce transaction costs.
• Political status – capital cities or devolved administrative centres receive extra public‑sector employment.
• Historical legacy – former industrial or colonial hubs often retain infrastructure and status.

These factors interact; for example, a new high‑speed rail line (connectivity) can stimulate the growth of tertiary services, raising the city’s functional rank – a clear cause‑and‑effect chain.

5. Types of national urban systems

1. Primate (primate) city system – one city dominates in size and functions. Examples: Paris (France), Bangkok (Thailand).
2. Balanced poly‑centric system – several cities of comparable size share national functions. Examples: Germany (Munich, Hamburg, Cologne, Frankfurt).
3. Dual‑city system – two major cities each hold important national roles. Examples: Sydney & Melbourne (Australia), Abuja & Lagos (Nigeria).

6. Urban structure and the forces that cause change

6.1 Horizontal (land‑use) structure

• Central Business District (CBD) – high‑rise offices, retail, finance.
• Inner‑city residential – mixed‑use, often undergoing gentrification.
• Suburban zones – low‑density housing, shopping parks, industrial estates.
• Edge‑city / office park – commercial development on the fringe, usually linked to a transport node.

6.2 Vertical structure

• High‑rise towers concentrate employment and housing in CBDs and major transport hubs.
• Mid‑rise and low‑rise dwellings dominate inner and outer suburbs, reflecting household size and affordability.

6.3 Forces that cause structural change (cause‑and‑effect)

• Transport improvements – new rail lines or ring roads can shift the CBD outward, create secondary CBDs (e.g., Manchester’s MediaCityUK).
• Economic restructuring – decline of manufacturing and rise of service/knowledge sectors move jobs from inner‑city factories to tertiary/quaternary clusters.
• Planning policies – green‑belt limits, mixed‑use zoning, regeneration incentives shape where growth occurs.
• Demographic trends – ageing populations, smaller household sizes, and lifestyle preferences affect demand for housing types and services.

6.4 CBD relocation and decentralisation

When a major transport node (e.g., a new railway station) is built outside the historic CBD, businesses may relocate to the new node, forming a “secondary CBD” or “edge‑city”. This process illustrates the interaction of transport, economic restructuring and planning policy, and it often leads to a re‑ranking of the city within the national hierarchy.

7. Sustainable urban development – challenges and strategic responses

8. Case study – Regeneration of London’s Docklands (1990‑present)

• Background – Once a thriving port, the Docklands entered decline in the 1970s, leaving high unemployment, derelict land and poor transport links.
• Key interventions
  • Creation of the London Docklands Development Corporation (LDDC) – a quasi‑governmental body with planning powers to fast‑track development.
  • Transport upgrades: Docklands Light Railway (DLR), London City Airport, Jubilee Line extension (1999) – dramatically improved connectivity.
  • Mixed‑use development: Canary Wharf (financial services), residential towers, public plazas, and the “London Riverside” scheme.
• Quantitative outcomes (2000‑2022)
  • Population grew from ~30 000 (1980) to >120 000 (2022) – a 300 % increase.
  • Employment: ~120 000 jobs created, of which ~45 % are in finance, law and professional services (tertiary/quaternary).
  • Housing: 30 000 new homes built; however, median house price in Canary Wharf is ~£1.1 million (2022), far above the London average (£530 k).
  • Transport: DLR passenger numbers rose from 10 million (1990) to 45 million (2021), reducing car‑dependency for commuters.
• Evaluation – economic, social‑equity and environmental dimensions
  • Economic success – creation of a new tertiary/quaternary hub, diversification of London’s service base, and substantial increase in tax revenue.
  • Social equity – high property prices have limited affordable housing; original low‑income residents were displaced or forced to commute long distances, highlighting a gap in the “diversity/equality” syllabus objective.
  • Environmental sustainability – regeneration of brownfield sites reduced pressure on greenfield development, but increased energy demand of high‑rise towers and limited green space have raised concerns about urban heat islands.
• Lesson for policy – Successful regeneration requires integrated planning that couples economic growth with affordable‑housing provision and environmental mitigation to meet the sustainability agenda.

9. Implications of the hierarchy for policy and planning

• Higher‑ranked cities attract investment, creating regional disparities; “balanced‑growth” policies (e.g., devolved powers, enterprise zones) aim to stimulate lower‑ranked towns.
• Infrastructure spending is often concentrated on top‑tier cities, risking neglect of market towns and rural service centres.
• Decentralisation strategies (relocating government departments, creating secondary CBDs) can rebalance the functional hierarchy and reduce pressure on primate cities.
• Urban‑growth pressures (housing, congestion, pollution) are most acute in primate and global cities, demanding robust sustainability measures that address the syllabus concepts of challenges & opportunities and diversity/equality.

Suggested diagram

Summary

The hierarchy of urban areas provides a framework for understanding how population size, service complexity and economic base organise settlements within a country. It is shaped by historic legacies, political decisions, transport connectivity and demographic trends – all key geographic concepts. Recognising the hierarchy helps students analyse regional inequality, evaluate regeneration or decentralisation policies, and answer exam questions with clear cause‑and‑effect reasoning.

Potential exam questions

1. Explain the concept of a primate (primate) city and give two examples of countries where it occurs. In your answer, refer to the factors that create primacy.
2. Using a table, compare the functions of a metropolitan city and a regional city in the United Kingdom, highlighting differences in the functional hierarchy.
3. Discuss how improvements in transport infrastructure can alter a city’s position within the national urban hierarchy. Use at least one real‑world example.
4. Evaluate the successes and limitations of the London Docklands regeneration in terms of economic growth, social equity and environmental sustainability.
5. Analyse the advantages and disadvantages of a dual‑city system for national development, drawing on examples from Australia or Nigeria.