Night-time lights as an indicator of urban development

The largest cities in sub-Saharan Africa have been growing at a fastest rate than smaller, secondary cities over the period from 1992 to 2013. According to research by Melanie Krause and Richard Bluhm, which uses satellite data on night-time lights to track the growth of big cities, secondary cities have not been catching up with primary cities.

Their study of inner city lights, presented at the Royal Economic Society's annual conference at the University of Sussex in Brighton in March 2018, also reveals that African cities have become more fragmented over time. The cities have been moving towards a collection of disconnected neighbourhoods rather than one clearly discernible city centre.

The new data in this study on the brightness of city lights make it possible to identify clearly urban cores within cities, which are much brighter than the outskirts, allowing researchers to analyse the changing structure of cities as they grow.