The urban challenge.

TLDR: In some cities >250000 people are added to the total population each year as discussed by the authors in the developing world and 93% of the world urban population will increase between 1990 and 2020.

Abstract: In some cities >250000 people are added to the total population each year. Between 1950 and 1990 the worlds urban population increased from 730 million to 2.3 billion. Between 1990 and 2020 it is likely to double again to >4.6 billion. 93% of this increase will occur in the developing world. The total size of the urban population in the developing world overtook that of the developed world in the early 1970s and now stands at around 1400 million compared to around 900 million for the developed world. The rate of growth of urban population has slowed somewhat since the 1950s both in the developed world and the developing world. During the 1970s and 1980s China has pursued vigorous policies to limit urban growth as a result of which urban population growth dropped from >8% per year in the late 1950s to just 1.4% in the early 1980s. South and Southeast Asia experienced quite rapid urbanization: slightly over 4% per year from 1970-85. 26% of the regions population lived in urban areas in 1985. Latin America is the most urbanized region of the developing world with nearly 70% of the regions population living in urban areas. Africa is the most rapidly urbanizing continent with an average rate of growth of urban population of 5%/year from 1970-85. The remaining 9% of the developing worlds urban population is located in Western Asia (5%) Eastern Asia (4%) and the Pacific (.1%). The rapid growth of urban population has obvious implications for the infrastructure and service needs of cities. The failure to expand water supplies sanitation systems housing supply and transportation to match the growth of population has been a prime cause of misery in the cities of the developing world. Sketches of 3 of the worlds rapidly growing cities (Dar es Salaam Sao Paulo and Jakarta) illustrate the conditions and some of the grave problems which cities in the developing world encounter.