Why This Matters
When you see a question about megacities on your exam, you're not being asked to recite population figures—you're being tested on urbanization processes, push-pull migration factors, urban primacy, and the relationship between economic function and city growth. These cities didn't become massive by accident; each one illustrates specific geographic principles about why people concentrate in certain locations and what happens when they do.
Understanding the world's largest cities means understanding site and situation factors, the rise of global cities in the world economy, and the universal challenges of urban sustainability. As you study this list, focus on what type of city each one represents and why it grew where it did. Don't just memorize that Tokyo has 37 million people—know that it exemplifies a primate city with extraordinary economic pull factors in a highly urbanized nation.
Global Financial Command Centers
These cities sit at the top of the world city hierarchy, functioning as command-and-control centers for the global economy. Their growth stems from agglomeration economies—the clustering of financial services, corporate headquarters, and specialized labor that makes these locations irreplaceable nodes in global networks.
Tokyo, Japan
- World's largest metropolitan area at 37+ million—the definitive example of a primate city dominating its national urban system
- Global financial hub ranking alongside New York and London in the "command and control" tier of world cities
- Extreme land scarcity drives vertical development and some of the highest real estate prices globally, illustrating urban land-use competition
Shanghai, China
- China's largest city at 24+ million and its primary connection point to global trade networks
- Major port city whose situation on the Yangtze River delta made it a natural gateway for international commerce
- Rapid modernization visible in its skyline represents China's economic liberalization and integration into the global economy
New York City, USA
- 8+ million in the city proper—relatively modest, but its metropolitan influence extends across a massive urban agglomeration
- Premier global city serving as headquarters for the UN, major financial institutions, and multinational corporations
- Gateway city history shaped by immigration, making it a model for studying ethnic enclaves and cultural landscapes
Compare: Tokyo vs. New York City—both are top-tier global financial centers, but Tokyo demonstrates urban primacy (dominating Japan's urban hierarchy) while New York shares influence with Los Angeles, Chicago, and other U.S. cities. If an FRQ asks about urban primacy, Tokyo is your clearest example.
Megacities of the Global South
These cities represent the most dramatic urbanization trends of the 21st century, driven by rural-to-urban migration, natural population increase, and economic restructuring. They illustrate both the opportunities and challenges of rapid urban growth in developing economies.
Delhi, India
- 31+ million and growing rapidly—one of the fastest-expanding megacities, driven by massive rural-to-urban migration
- National capital combining political functions with industrial growth, creating diverse pull factors
- Severe air pollution makes it a textbook case for examining environmental costs of rapid urbanization
Mumbai, India
- India's financial capital at 20 million—demonstrates how economic specialization creates distinct urban hierarchies within a single country
- Bollywood headquarters and tech hub illustrating the concentration of creative and knowledge industries in global cities
- Extreme housing inequality visible in informal settlements like Dharavi alongside luxury high-rises
Dhaka, Bangladesh
- 20+ million in one of the world's most densely populated cities—a key example of urbanization outpacing infrastructure
- Textile industry hub linking the city to global commodity chains and illustrating export-oriented industrialization
- Climate vulnerability from flooding makes it a critical case study for urban resilience and climate adaptation
Karachi, Pakistan
- 16+ million as Pakistan's largest city and primary economic engine, though not the capital—an example of urban primacy without political primacy
- Port city situation on the Arabian Sea drives its commercial importance and industrial concentration
- Infrastructure deficits in water, sanitation, and transportation illustrate challenges of managing rapid informal growth
Compare: Delhi vs. Mumbai—both Indian megacities, but Delhi is a political capital while Mumbai is the economic capital. This split illustrates how different urban functions create different growth patterns and challenges. Mumbai's coastal site also creates distinct environmental pressures compared to Delhi's inland location.
Latin American Primate Cities
Latin America exhibits some of the world's strongest patterns of urban primacy, where a single city dominates the national urban system. Colonial history, centralized political systems, and infrastructure networks radiating from capitals all contribute to this concentration.
São Paulo, Brazil
- 22 million as South America's largest city—the economic engine of Brazil and the continent
- Industrial and financial center that grew explosively during 20th-century import substitution industrialization
- Social inequality visible in stark contrasts between wealthy neighborhoods and peripheral favelas
Mexico City, Mexico
- 21+ million built on the site of the Aztec capital Tenochtitlan—illustrating how site factors persist across centuries
- Classic primate city containing a disproportionate share of Mexico's economic activity, government, and cultural institutions
- Subsidence and air quality issues stem from its basin location, making it a case study in urban environmental challenges
Buenos Aires, Argentina
- 15 million with strong European architectural influence—reflecting historical migration patterns and cultural diffusion
- Port city situation on the Río de la Plata made it the gateway for Argentina's agricultural exports
- Economic volatility has created cycles of growth and decline, illustrating how global economic integration affects urban fortunes
Compare: São Paulo vs. Mexico City—both are massive Latin American primate cities, but São Paulo grew primarily through industrialization while Mexico City's dominance stems from its role as political capital since pre-Columbian times. This distinction matters for FRQs about urban growth factors.
Asian Political and Industrial Centers
These cities combine political capital functions with industrial development, illustrating how government policy and economic planning shape urban growth. State-directed development, special economic zones, and infrastructure investment have accelerated their expansion.
Beijing, China
- 21+ million as China's political and cultural capital—the center of government power for centuries
- Historical landmarks like the Forbidden City alongside modern development show layers of urban morphology
- Severe pollution challenges resulted from rapid industrialization, prompting aggressive environmental policy responses
Chongqing, China
- 30+ million in its administrative region—though this includes substantial rural areas, illustrating how Chinese city boundaries differ from Western definitions
- Interior development hub as part of China's "Go West" policy to reduce coastal-interior inequality
- Transportation node where the Yangtze River meets major rail lines, demonstrating classic situation advantages
Osaka, Japan
- 19 million in the Kansai metropolitan area—Japan's second city and historical commercial center
- Industrial and port functions complement Tokyo's financial dominance, showing functional specialization within national urban systems
- Culinary and cultural distinctiveness from Tokyo illustrates how large cities within the same country develop unique identities
Compare: Beijing vs. Shanghai—Beijing is the political capital focused on government and culture, while Shanghai is the economic capital oriented toward global trade. This functional division is common in large countries and frequently appears in exam questions about urban hierarchies.
Transcontinental and Historical Crossroads
Some cities derive their importance from strategic location at the intersection of major trade routes, cultural zones, or physical geography. Their growth reflects centuries of accumulated situational advantages.
Istanbul, Turkey
- 15+ million straddling Europe and Asia—the only major city spanning two continents
- Historic trade route convergence at the Bosporus Strait has made it strategically vital for millennia
- Cultural layering from Byzantine, Ottoman, and modern Turkish periods creates a complex urban landscape
Cairo, Egypt
- 20+ million as the Arab world's largest city—a primate city dominating Egypt's urban hierarchy
- Nile River site provided the water and agricultural surplus that supported urban growth for thousands of years
- Informal housing expansion into agricultural land and desert illustrates pressures on urban peripheries in developing regions
Compare: Istanbul vs. Cairo—both are historically significant cities that dominate their regions, but Istanbul's importance stems from controlling a strategic strait while Cairo's derives from the Nile River's resources. Both illustrate how site and situation factors from ancient times continue shaping modern urban geography.
Quick Reference Table
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| Urban Primacy | Tokyo, Mexico City, Cairo, Buenos Aires |
| Global Financial Centers | Tokyo, New York City, Shanghai |
| Rapid Urbanization (Global South) | Delhi, Dhaka, Karachi |
| Port City Situation | Shanghai, Mumbai, Karachi, Buenos Aires |
| Political vs. Economic Capital Split | Delhi/Mumbai (India), Beijing/Shanghai (China) |
| Environmental Challenges | Delhi (air), Mexico City (subsidence), Dhaka (flooding) |
| Colonial/Historical Site Persistence | Mexico City, Cairo, Istanbul |
| Industrial Growth Centers | São Paulo, Chongqing, Osaka |
Self-Check Questions
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Which two cities best illustrate the distinction between a country's political capital and economic capital, and what geographic factors explain this functional split?
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Compare Tokyo and New York City as global financial centers—how do they differ in terms of urban primacy within their national urban systems?
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If an FRQ asks you to explain environmental challenges facing megacities in developing countries, which three cities would you choose and what specific challenge would you highlight for each?
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Delhi, Dhaka, and Karachi are all rapidly growing South Asian megacities. What common push-pull factors explain their growth, and what infrastructure challenge do they share?
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How does Istanbul's location illustrate the geographic concept of situation, and how does this compare to Cairo's site advantages along the Nile?