Figure 7.2 shows urbanization over time and across income levels over the quarter century from 1970 to 1995. Each line segment represents the trajectory of one country, starting from the solid dots, which represent the 1970 income and urbanization level for a given country and ending at the end of the line segments (marked by a diamond), which represent the corresponding 1995 income and ur- banization level for the same country. Although the World Bank caption to the figure stated that “urbanization is closely associated with economic growth,” the figure may also be interpreted as showing that urbanization is occurring every- where, at high and low levels of income and whether growth is positive or nega- tive. Even when the lines point to the left, indicating shrinking incomes per capita over the period, they still generally point upward, indicating that urban- ization continued. In short, urbanization is happening everywhere in the world, although at differing rates. So we need to consider urbanization carefully—is it only correlated with economic development, or is causation also at work?
Indeed, one of the most significant of all modern demographic phenomena is the rapid growth of cities in developing countries. In 1950, some 275 million