Measuring the Human Urban Footprint

Density Levels and Population Size of 129 Metropolitan Regions

Following on from the analysis of urban well-being, the data on these pages shows the result of a new mapping exercise that covers the same 129 ‘extended metropolitan regions’ across the world, with a total population of 1.2 billion people, representing 35 per cent of the world’s urban population in 2010. From Cotonou in Benin, with just more than 1.5 million people, to the Tokyo metropolitan region, with more than 42 million inhabitants, our study both measures and illustrates density patterns in urban regions across all five continents, expanding LSE Cities’ longstanding interest in the links between physical and social form. Using Google Earth satellite imagery, we captured a ‘snapshot’ of where people live and estimated ‘net densities’ by systematically tracing the built-up area of each metropolitan region – including central zones, satellite towns and the peripheral areas (a detailed methodology can be found online). The fact that 23 million people in Manila occupy a space one eighth the size of the same number of New Yorkers, or that Atlanta in the USA is 25 times larger than Hong Kong with roughly the same population, says something about the capacity and resilience of urban form as well as physical and geographical constraints.

The map above shows the size of the extended metropolitan regions and their density, with darker blue indicating greater concentration of people and lighter blue more sparsely populated city regions. It shows that density levels vary significantly across and within world regions, with the highest densities concentrated in North Africa, the Middle East, South and South-east Asia and – not surprisingly – more sprawling cities in North America and Australia.

To get a sense of the spatial dynamics of these city regions, we mapped 12 cases at the same scale with core built-up areas in black and peripheral areas in grey. By comparing the footprint of the world’s largest urban conurbation in Tokyo with Atlanta, our sample’s most land-hungry city region, we see that roughly the same amount of land is occupied by 42 million as by 7.5 million people. Meanwhile, the map of London shows that 14 million people are spread across South-east England.

Some of the densest metropolitan regions in the world are illustrated opposite, arranged in three rows in descending order of density. Lahore, Hong Kong and Kinshasha – where more than nine million people live in 368 square kilometres (228 square miles) of single storey housing – reveal very diverse spatial patterns of hyper-density. Cairo, Manila and Bogotá represent diverse African, Asian and South American typologies of average high density, while Lagos, Lima and Ho Chi Minh City accommodate radically different population sizes with similar levels of density.

Source: The population of the Extended Metropolitan Regions were based on national statistical sources and the UN World Urbanisation Prospects, 2009 Revision. All other information was calculated from Google Earth Pro satellite imagery (various years).