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What does “urban” mean?

Chandan Deuskar's picture
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This aerial view of Hanoi, Vietnam, clearly shows areas of decreasing density between the city and the countryside, making it hard to define the limits of the "urban" area.
Anyone reading this blog is likely to have heard the statistic that ‘over half of the world’s population now lives in urban areas’. This has been the standard opening line of reports and presentations about urbanization since this milestone was supposedly reached in 2008. But what does it really mean?

In everyday usage, terms related to human settlements have vague, shifting meanings. What one person might describe as a small ‘city’ might be a ‘town’ or ‘village’ for someone else; one person’s ‘megacity’ might be a cluster of cities from a different perspective. Similarly, we can usually identify areas that are clearly within a city and others that are outside it, but there is usually a peri-urban area of intermediate density that usually lies between the two, making it hard to define a clear city limit. Formal administrative boundaries may have historic or political meaning, but are rarely aligned with the physical or economic extents of the urban area.

What exactly is a city? It depends who you ask

It turns out there is no standard international definition of an ‘urban’ area or ‘urban’ population. Each country has its own definition, and collects data accordingly. The statistic that 50% of the world’s population is urban is arrived at simply by adding up these incomparable, and sometimes conflicting, definitions.
 

Despite expectations, cities in East Asia are becoming denser

Chandan Deuskar's picture

 
When we think of urban expansion in the 21st century, we often think of ‘sprawl’, a term that calls to mind low-density, car-oriented suburban growth, perhaps made up of single-family homes. Past studies have suggested that historically, cities around the world are becoming less dense as they grow, which has prompted worries about the environmental impacts of excess land consumption and automobile dependency. A widely cited rule of thumb is that as the population of a city doubles, its built area triples. But our new study on urban expansion in East Asia has yielded some surprising findings that are making us rethink this assumption of declining urban densities everywhere.