Source: United Nations Population Division.
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- Conventional cities that have been the political and commercial centers of their respective civilizations for centuries. They usually commanded access to an immediate large agricultural hinterland capable of supporting their large populations (by historical standards). These include Beijing, Guangzhou, Istanbul, Mumbai, Cairo and St. Petersburg. Some of them where (former) colonial cities (e.g. Havana, Mexico) acting as commercial and administrative centers for European interests.
- Modernizing cities driven by the industrial revolution and its demographic transition, most of them in Europe. These include London, Paris, New York, Berlin, Philadelphia and Liverpool. Many of these cities were of small size prior to the industrial revolution, which permitted the realization of their economic potential and specialization. Some were manufacturing centers, commercial gateways or resource collection centers.