The process by which there is an increase in the number of people living in urban areas; or
The increase in the land area occupied by towns and cities
Of these definitions, the first is by far the most useful, but it does contain some difficulties. The number of people living in cities can be expressed as an absolute figure, but it is more commonly given as a percentage of the total population of a country. If rural populations are also growing, then the relative rate of increase of urban population may not appear as significant as it would do if rural populations were stagnating or declining.
We need to define our terms. Here are some common methods used to define towns. Population size: highly arbitrary and likely to vary from country to country. Population density: always going to require the use of an arbitrary division as modern cities merge with the surrounding countryside. Function: what do cities do? This was much easier to answer in the past than today. Level of administration: e.g. rural or urban district. This is a common way of escaping the need to define by adopting the existing local government designations.
The UN does not classify settlements as towns or rural areas. Instead it has chosen to classify settlements by size. This causes variations depending on the census methods of individual countries, which make the figures for city size unreliable in detail, but the ‘big’ picture emerges clearly enough.
Table 1: Number of cities with more than 1 million people, by region, 1800-2000 Region 1800 1900 1950 2000 Africa 0 0 2 34 Asia 1 3 26 136 Europe 1 9 30 61 Latin America 0 0 7 39 North America 0 4 14 36 Oceania 0 0 2 5 Total 2 16 81 311
Table 2: Distribution of the world’s 100 largest cities, 1800-2000 Region 1800 1900 1950 2000 Africa 4 2 3 6 Asia 64 23 32 44 Europe 29 51 37 19 Latin America 3 5 8 16 North America 0 16 18 13 Oceania 0 2 2 2
It is worth remembering that there is no pre-determined path here. Urban growth has causes and if those factors are not in place, then growth will not occur. The history of the world is not pre-ordained. Africa may or may not reach the same levels of urbanisation as other continents, but beware of ‘explanations’ that suggest a known outcome. This is what is known as teleological reasoning and it is thoroughly misleading .
A relatively recent feature of urbanisation has been the emergence of mega-cities with populations of over 5 million. These were once almost exclusively found in the highly developed economies of Europe, the USA and Japan and were associated with enormous concentrations of wealth and power. Although these cities persist and remain economically dominant, a new breed of mega-city has emerged. These are far more widely distributed and are largely a consequence of forces in rural areas rather than positive pull factors in the urban areas concerned.