Mid-20th century to present: massive rural-to-urban and internal migration. Metro population >21 million.
City expanded beyond original boundaries into neighboring states (México, Hidalgo), consuming farmland and natural areas.
Migrants from all Mexican regions and abroad created a melting pot—evident in food, music, art, festivals, languages.
Migrant labor fuels manufacturing, construction, services, commerce. But also increases competition for jobs and housing.
Poverty belts, informal settlements (colonias populares), inequality, crime, strained public services.
Air pollution (valley trapping), water scarcity, aquifer depletion, waste management, loss of green space.
Managing this growth sustainably is Mexico City's defining 21st-century challenge.