It is estimated that between 60% and 70% of the GDP of Latin America and the Caribbean is generated in urban areas, where industry and services are usually concentrated (UN-Habitat, 2012). This output is further concentrated in just a few cities. The 40 largest cities in Latin America and the Caribbean generate over one third of regional GDP, and virtually half of that output comes from four megacities: Sao Paulo, Mexico City, Buenos Aires and Rio de Janeiro. Large cities are generally an aggregation of local municipalities and governments, which complicates urban management and planning (ECLAC 2012d).