Megacity

A megacity is a very large city, typically with a population of more than 10 million people. The United Nations Department of Economic and Social Affairs (UN DESA) in its "World Urbanization Prospects" report defines megacities as urban agglomerations with over 10 million inhabitants. Reports from academics, the European Council, the Organisation for Economic Co-operation and Development delineate them as the metropolitan areas that are inhabited by more than a total population of 10 million people. The fast growth of the former is attributed to the proliferation of the latter. Infrequently in some sources, from five to eight million is considered the minimum threshold, along with a population density of at least 2,000 per square kilometre. The terms conurbation, metropolis, and metroplex are also applied to the latter. The total number of megacities in the world varies between different sources and their publication dates. The world had 32 according to EU Global Human Settlement Layer (2024), 33 according to UN DESA (2025), 39 according to the OECD (2020), and 42 according to Demographia (2025). In total, at most 46 unique places are mentioned as megacities across these selected sources, although some of these are just agglomerated differently between them. A good percentage of these urban agglomerations are in the Global South's most populous countries – China and India. The other three-to-five countries with more than one megacity are Brazil, Indonesia, Japan, Pakistan, and the United States. African megacities are present in Angola, Democratic Republic of the Congo, Egypt, Nigeria and South Africa; European megacities are present in France, Germany, Russia, the United Kingdom, and Turkey (also in Asia); megacities can be found in Latin America in the countries of Brazil, Mexico, Colombia, Peru, and Argentina. Many recent satellite image-based sources identify China's Pearl River Delta (anchored by Guangzhou) as the...