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The Components of Urban Growth in Developing Countries

This report is concerned with the question of what share of urban population growth is due to natural increase and what share is due to rural to urban migration flows. This question is particularly salient in developing countries, where more of the world’s population growth is occurring and where urbanization trends are the fastest. This study revisits the issue of the driving mechanism for urban growth, aiming to assess the relative contribution of natural increase and rural to urban migration. This issue has been considered in two prior publications of the United Nations. The first provided both a broader discussion of urban and rural population growth more generally, as well as a presentation of the method for studying the components of urban growth using the Census Survival Ratio Method (United Nations 1980). The second report continued the analysis on the components to urban growth with the same basic methodology and using updated data from a larger number of countries (United Nations 2001). The current study greatly expands the empirical range by including data on 248 censuses from 76 countries. We focus attention on certain specific assumptions underlying the methodology. In particular, we examine the methodological limitations to help to understand the extent to which the overall assessment of the components of growth may (or may not) be affected by these assumptions. These additional analyses provide further insight into the sensitivity of estimates of the components of urban growth.