GGRA03U3 – Week 5
What are Megacities?
- Current UN Definition:
o Population>10m (million)
- In the past various definitions, including 4m (Dogan and Kasarda 1988), 8m (Richardson
1993, Gilbert 1996), 10m (Ward 1990, UNDESA 2008)
- There is no reason to think that there is a qualitative difference between cities of 8 or
- There clearly is a difference between cities of 1m and 8-10m.
- What urban issues are likely to be impacted by very large size?
As cities get larger, growth happens in the edges.
o Travel issues
o Poverty and Social Inequalities
Exists in larger cities, or simply more?
o Larger housing problems for the poor
Why are Megacities important?
- Megacities now contain about 9% of world urban population
- Rapid growth of number of megacities, 2 in 1950, by 1975 Mexico City was third, by
2007, there was 19 including 15 in developing countries
- In 2025, it is projected that there will be 28, with 22 in developing countries
- This is clearly an increasingly important share of total urban population
- Understanding the problems and solutions characteristic of megacities is essential.
- In what ways are megacities a new form of urban development?
- Is this a qualitative change, or merely a quantitative change?
- What are the distinctive characteristics of megacity urbanization compared to smaller
- What are the advantages and disadvantages of megacities? - What major policy challenges can be expected?
- What responses are we already seeing?
Key Concept 1
- Megacities represent a new urban scale.
o Megacities are city-regions with more than 10m population
o Most megacities are in developing countries
o The number of megacities is growing rapidly
o Population and urban projections for the next 40 years are known with relative
o Megacities are a qualitatively different urban form, not just bigger – for 5 main
Land values and housing
- Scale is a major geographical concept
- A city of 100,000 will function utterly differently than a city of 5 million, even with similar
GDP/capita, population density, housing types, and jobs
- Methodological scale refers to the scale at which phenomena are studied (boundaries,
- Geographical scale refers to scales that may be inherent in the object of study – the
body, neighbourhood, city, region, nation, globe – these produce relationships and power
- Geographic scale differentiates between spatial phenomena, and spatial processes.
Special Issues of Very Large-Scale Cities
- There has been a very long history of thinking about city size
- Plato and many others identified 50k as an ideal size
- At that size, it is possible to know everyone, participatory democratic governance is
possible - In 20 century many predicted that over a certain size a range of Diseconomies of Scale
would become dominant, and would increase costs, and reduce efficiency, therefore
leading to slower growth.
- Economy of Scale:
o The more products are made, the cheaper they are.
Hand-made vs. Factory made
- Diseconomy of Scale:
o The larger the product, the more costly
Large name brands
- What is a diseconomy of scale, and what are some examples?
Pollution increases as cities grow.
Special Issues of Very Large Cities – 2
- Expected diseconomies of scale are congestion, pollution, long travel times, high land
- All of these can be expected to continue to increase with population growth.
- Such factors will increase the costs of business, and of living in large cities, but can be
reduced by increased infrastructure investment, roads, subways, etc.
- Counterbalancing these increased costs are economies of scale, where there are
economic advantages to larger city size
Special Issues of Very Large Cities – 3
- Expected economies of scale:
o Larger markets & larger labour pools
- Higher land costs result in more efficient use of land, some goods are available that are
not available in smaller cities
- Subways, opera houses, specialist services, stock markets, etc.
- If a large city continues to grow, we might conclude that economies of scale are larger
than diseconomies of scale
- BUT, it is important to realize that diseconomies of scale mostly cost individuals, while
economies of scale mostly benefit firms. Costs to people Benefits to Firms
- That sounds pretty unfair, why would that make sense?
- Why would extra costs affect people more than firms?
- They all affect livability – pollution, high housing costs, higher housing costs, long travel
times all are major costs to individuals
- For many firms, the benefits of large labour pools, larger nearby market, and access to
specialist services and suppliers very often outweigh higher land and travel costs
Key Concept 2
- Megacities demonstrate a number of special characteristics
o There have been debates about ‘optimal city size’ for centuries. We cannot
determine a ‘best size’ for cities.
o Idea of diseconomies of scale is that for some issues very large size will mean
higher costs: c