Urban and rural age structure gaps in Africa

Ashira Menashe-Oren, Hebrew University of Jerusalem

Urbanisation is a complex process shaped by mortality, fertility and migration and in turn altering demographic rates and social structures. Countries in Africa continue to be predominantly rural, still in the midst of an urban transition. Urban centres play key roles in economic development and lead demographic transitions. During the course of the demographic transition age structures shift from young to old ones resulting in fundamental implications. However with urban/rural variance in the timing and pace of transition, within country dynamics should be considered. Diverging age structures may have socio-structural consequences, hindering development. This research focuses on gauging the extent of the urban/rural gap in age structure in Africa over the past 35 years and how this may change over the course of the demographic transition. It also focuses on understanding the mechanisms driving these gaps, rural-to-urban migration and differing rates of natural increase. United Nations estimates of rural and urban populations by sex and age are used for 50 African countries from 1980 to 2015 to calculate aggregate measures of age compositional urban/rural differences. Building on the Census Survival Ratio Method which provides an estimate of rural-to-urban migration flows, the primary causes of change in age structure are decomposed. Results indicate that urban median ages are higher than rural ones in all countries and increase over time in both sectors. Over the course of the demographic transition the gap in urban/rural age structures grows until late stages of transition where the gap decreases. Rural-to-urban migration plays a role in restraining the age structure gap throughout the demographic transition, though to a lesser extent in late stages of transition. These results indicate that development may only be an urban phenomenon with the population gap adding to urban bias, until late stages of the demographic transition are reached.