This exploratory map shows data from the fantastic Global Human Settlement Layer (GHSL) produced by the European Commission. Integrating huge volumes of satellite data with national census data, the GHSL has applications for a wide range of research and policy related to urban growth, development and sustainability, and is available as open data. The dataset encourages understanding of the complex hierarchy of human settlement, rather than making simple rural-urban divisions. Each cell represents population density at either 1km resolution or 250m resolution depending on the zoom level.
Megaregions and Diverse Urban Forms
In the early 20th century, geographers like Patrick Geddes observed how rail and road networks were allowing rapidly growing cities to fuse together into vast sprawling conurbations. A classic example is the northeastern seaboard of the USA (click on links to focus the map), a megalopolis as Gottman termed it, stretching hundreds of miles from Washington to Boston, with around 55m people.
The GHSL data shows how widespread urban megaregions have become. China has many, the largest being the Pearl River Delta region with around 60m people, and the Yangtze River Delta megaregion with around 70m.
Another related form of megaregion comes from areas of dense agriculture that begin to urbanise with loser patterns of small scale industry. McGee first used the term desakota (“village-city”) in relation to the incredible form of Java in Indonesia, with the densities of urban hinterlands greatly exceeding Western cities but with activity patterns remaining dispersed and linked to agriculture. Similar desakota patterns can be seen in Kolkata, Dhaka, Lahore and Beijing regions, and increasingly in several regions of Sub-Saharan Africa including Nigeria and surrounding Lake Victoria, though with much diversity in each case.
Density and Development
Urban densities are linked to cultures of living, with regions like Latin America and East Asia noted for high density urban forms. Higher population densities can also be linked to affluence, as in poorer countries transport infrastructure is less developed and housing used more intensively. The highest density cities in the world are in South and South East Asia, such as Mumbai, Dhaka and Manila (note this depends how density is measured- see the Analysis page).
But these cities are more prosperous than neighbouring rural areas, and high densities can also be linked to affluence. Singapore, Hong Kong and Seoul combine extremely high densities with very high levels of prosperity. The richest large western cities, like London, Paris, New York and San Francisco are also relatively high density and intensifying.
Another important aspect of density is its relationship with travel demand and energy use. There are many examples of huge urban regions at very low densities, most evidently in the USA with metro regions such as Atlanta and Houston. Unsurprisingly these cities have the highest rates of transport energy use and carbon emissions in the world.
Sprawl is not however limited to the USA, and similar forms at a smaller scale can be seen in countries like Australia and Canada. The industrial heartland of Europe that follows the river Rhine through western Germany to Belgium and the Netherlands, is notably dispersed and low density.
Traces of Ancient Civilisations
As well as exploring contemporary urbanism, many historic patterns remain engraved in the landscape of human settlement. Ancient cities first appeared by fertile rivers that could support the intensive agricultre needed to feed an urban population. Egypt spectacularly displays the contrast between the arid Sahara and the rich lands fertilised by the Nile’s annual inundation. This landscape has supported urban civilisation for around 5000 years.
The oldest cities we know of were on the Tigris and Euphrates river deltas, near modern day Basra in Iraq. Another important ancient civilisation grew around the Indus Valley near Hyderabad in modern day Pakistan.
As well as rivers, some ancient transport links are visible in modern settlement patterns. The Roman road Via Aemilia cut across Northern Italy, through what is now Bologna and Parma. Its precise straight form is still evident 2000 years after its completion.