Built-up expansion between 2001 and 2011 in South America continues well beyond the cities

The expansion of built environment is a major driver of land change which can have irreversible consequences on the environment, ecosystem services, and biodiversity. While most studies have focused on urban areas, particularly large cities, the built environment includes much more. This is exemplified by the complex interconnection among cities of all sizes and rural areas through trade, people, policies, and infrastructure, which ultimately shapes the patterns of land use. However, a comprehensive spatial analysis of built-up areas is lacking. Here, we used nighttime data to evaluate the extent and spatial distribution of the built environment across the South American continent between 2001 and 2011, with the objectives of determining where built-up expansion is occurring and the relative contribution of the 30 major cities with populations greater than 1 million people. Our results reveal that built-up expansion occurs well beyond the 30 major cities, with the majority of expansion occurring in small and medium cities and rural areas. This detailed and spatially explicit description of development patterns across South America provides a valuable baseline for land use policies, which hopefully will balance future built expansion with the need for agriculture lands and the protection of large uninterrupted natural areas.