The similar size of slums

More than half of the world's population currently resides in urban areas. In the majority of developing countries slums are a defining part of the urban scape. Their supply with energy, basic infrastructure, among others is one of the main challenges of modern civilizations. To provide an optimal supply, the spatial patterns of slums in cities have to be explored. While most of current literature is focused on inter-urban dynamics, this paper is focused on intra-urban pattern (i.e. the spatial pattern of morphological slums within a city) and its link to the inter-urban ones. Therefore, census and remote sensing data are analyzed to create rank size distributions of morphological slums in different cities of developing countries. The observations were compared to rank size distributions of cities in a respective developing country. It is found that typical inter-urban pattern can be transferred to intra-urban pattern. Surprisingly is the fact that the size of slums is independent from city and global region in the analyzed cities. The slums in Mumbai, Manila, Rio de Janeiro and Cape Town have an average area of 0.016 km2 with a standard deviation of only 0.004 km2.