Megacities by the Numbers

Examine urbanization trends shaping global demographics

2 min read

Samuel K. Moore is IEEE Spectrum’s semiconductor editor.

URBANIZATION

Urban and rural population growth, 1950-2030. Urban increases, rural plateaus after 2000.Source: WORLD URBANIZATION PROSPECTS, 2005 REVISION (UNITED NATIONS)

By 2008, for the first time in history, half of the world’s population will live in urban areas. By 2030, 4.9 billion people, or 60 percent of the world population, will be urban.

WEALTH

Bar chart of major cities' GDP growth from 2005 to 2020; Tokyo leads, followed by New York City.

Source: World Urbanization Prospects, 2005 Revision (United Nations)

In 2005, megacities accounted for 9 percent of the world’s US $59.4 trillion gross domestic product. Five megacities—Los Angeles, Mexico City, New York City, Osaka-Kobe, and Tokyo—were among the world’s 10 richest. Those five combined were more than twice as rich as the other 15. GDP will grow on average 4.9 percent per year across 22 megacities by 2020, when their combined GDP will reach $9.4 trillion. NOTE: ALL GDP USES THE PURCHASING POWER PARITY METHOD.

MEGACITIES

3D world map chart showing city populations for 1975, 2005, and 2015 in millions.

Source: UNITED NATIONS HUMAN SETTLEMENTS PROGRAMME (UN-HABITAT) URBANINFO DATABASE

Since 1975 the number of urban agglomerations with a population of 10 million or more—megacities by the United Nations’ definition—grew from just three to 20. By 2015 two more cities, Istanbul and Guangzhou, will cross the 10 ­million mark. Megacities account for 9.4 percent of the world’s urban population. The growth of mega­cities is predicted to slow over the coming decade, and in 2015 they will still account for nearly the same proportion of the urban population that they do now.

AND POVERTY

Bar chart of rising world slum population from 1990 to 2020, reaching 1500 million in 2020.

SOURCE: THE WORLD BANK DEVELOPMENT ECONOMICS RESEARCH GROUP ESTIMATES

In the face of this GDP growth, the world slum population could swell from 998 million in 2005 (estimated) to 1.4 billion in 2020, assuming efforts to stem this growth do not succeed. In four of the 10 countries with the highest slum populations in 2001, slum dwellers made up a majority of the urban population. Except for Iran, each of the 10 contained at least one megacity.

AIR POLLUTION

Bar chart of pm10 levels; Karachi highest, New York City lowest.

SOURCE: UNITED NATIONS HUMAN SETTLEMENTS PROGRAMME (UN-HABITAT) URBANINFO DATABASE

Particulate matter smaller than 10 micrometers in diameter (pm10) is the most dangerous to human health, because it can pass through the nose and throat and enter the lungs—leading to asthma, lung cancer, cardiovascular problems, and premature death. Of the megacities, Karachi, Pakistan, had by far the worst pm10 problem in 1999, the last year for which complete data were available. New York City had the cleanest air.

SERVICES

2003 home utilities access: electricity, sewers, piped water in 7 cities; Shanghai lacks data.

Source: TeleGeography, a division of PriMetrica Inc.

Some large megacities in the developing world have done a better job at providing a connection to the electric grid than to the sewage and water systems. The United Nations has gathered such data on only eight of the 15 developing world megacities.

Connections

Map showing high-capacity internet routes, with London-New York at 387 Gb/s as the highest.

Source: TeleGeography, a division of PriMetrica Inc.

Among the 50 highest capacity international city-to-city Internet routes in 2006, 12 connect to megacities—New York City, Tokyo, Los Angeles, and São Paulo (listed in order of bandwidth). Those 12 connections combined carried up to 924 gigabits per second of data. At 387 Gb/s, the London-to-New York connection is the highest capacity in the world.


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