AP Human Geography – World Cities and Rank-Size Rule / Primate City Rule

AP Human Geography – World Cities and Rank?Size Rule / Primate City Rule

AP Human Geography Study Guide: World Cities & Rank-Size Rule / Primate City Rule

What This Is

This topic explains how cities are organized in a country’s urban hierarchy—whether they follow a predictable pattern (Rank-Size Rule) or are dominated by one massive city (Primate City Rule). The AP exam tests your ability to compare these models, identify real-world examples, and analyze their economic/social effects. For example, France’s primate city is Paris (over twice as large as the next city, Marseille), while Germany follows the Rank-Size Rule (Berlin, Hamburg, Munich, etc., decrease in size predictably). Understanding these patterns helps explain urbanization, economic development, and regional inequality.

Key Terms & Concepts

• Urban Hierarchy: A ranking of cities based on population size and economic/social influence. Larger cities offer more specialized services (e.g., universities, airports) than smaller ones.
• Rank-Size Rule: A pattern where the nth largest city is 1/n the size of the largest city. Formula: Population of nth city = Population of largest city / n Example: If the largest city has 10 million people, the 2nd largest should have ~5 million, the 3rd ~3.3 million, etc.
• Primate City: A city that is disproportionately larger (at least twice the size of the next largest city) and dominates the country’s economy, politics, and culture. Example: Mexico City (22M) vs. Guadalajara (5M).
• Central Place Theory (Christaller): Explains how cities provide goods/services to surrounding areas. Larger cities serve larger regions with specialized services (e.g., heart surgeons), while small towns offer basic needs (e.g., gas stations).
• Megacity: A city with 10+ million people (e.g., Tokyo, New York, Mumbai). Often face challenges like pollution, traffic, and housing shortages.
• World City (Global City): A city with global economic/political influence (e.g., New York, London, Tokyo). Ranked by financial power, cultural reach, and connectivity (e.g., stock exchanges, airports).
• Metacity: A city with 20+ million people (e.g., Delhi, Shanghai). Often in developing countries with rapid urbanization.
• Urban Primacy: When a primate city dominates a country’s urban system, leading to uneven development (e.g., Lagos, Nigeria vs. other Nigerian cities).
• Gravity Model: Predicts interaction between cities based on population size and distance. Formula: Interaction = (Population? × Population?) / Distance² Example: New York and Los Angeles interact more than New York and a small Midwestern city.
• Network City: Cities connected by high-speed transportation/communication (e.g., Boston-NYC-Washington, D.C. corridor).
• Forward Capital: A capital city relocated to promote development (e.g., Brasília, Brazil moved inland to shift growth away from Rio de Janeiro).
• Overurbanization: When a city’s population grows faster than its infrastructure (e.g., Karachi, Pakistan, with slums and water shortages).

Step-by-Step: How to Analyze Rank-Size vs. Primate City Patterns

1. List the top 5 cities by population for a given country (use data from the AP exam or a reliable source like the UN).
2. Calculate expected sizes using the Rank-Size Rule:
3. If the largest city has 12 million, the 2nd should be ~6 million, the 3rd ~4 million, etc.
4. Compare actual vs. expected sizes:
5. If the 2nd city is much smaller (e.g., 3 million vs. 6 million), it’s a primate city pattern.
6. If sizes closely match the formula, it follows the Rank-Size Rule.
7. Explain the implications:
8. Primate City: Uneven development, brain drain from smaller cities, overcrowding (e.g., Bangkok, Thailand).
9. Rank-Size Rule: More balanced development, better distribution of services (e.g., U.S., Germany).
10. Check for exceptions:
11. Colonial history? Primate cities often result from colonial centralization (e.g., Lima, Peru).
12. Government policies? Some countries build new capitals to reduce primacy (e.g., Abuja, Nigeria replaced Lagos).

Common Mistakes

• Mistake: Assuming all large cities are primate cities. Correction: A primate city must be at least twice as large as the next city. Example: New York (8.5M) vs. Los Angeles (4M)—not a primate city because the ratio is ~2:1, not 2+:1.

• Mistake: Confusing megacities with world cities. Correction: A megacity is defined by population size (10M+), while a world city is defined by global influence (e.g., Tokyo is both; Kinshasa is a megacity but not a world city).

• Mistake: Thinking the Rank-Size Rule applies to all countries. Correction: It works best in developed countries with balanced economies (e.g., U.S., Germany). Developing countries often have primate cities (e.g., Argentina’s Buenos Aires).

• Mistake: Ignoring historical/political factors in primate cities. Correction: Primate cities often result from colonialism (e.g., Dakar, Senegal) or centralized governments (e.g., Paris, France).

• Mistake: Forgetting that forward capitals can reduce primacy. Correction: Countries like Brazil (Brasília) and Nigeria (Abuja) moved capitals to decentralize power and promote regional growth.

AP Exam Insights

1. FRQ Likely Scenarios:
2. Data analysis: Given a table of city populations, identify the pattern (rank-size vs. primate) and explain its economic/social effects.
3. Map-based question: Compare urban hierarchies in two countries (e.g., U.S. vs. Mexico) and explain why they differ.

4. Theory application: Use Central Place Theory to explain why a small town lacks a hospital but a nearby city has one.

5. Multiple-Choice Traps:

6. “All megacities are world cities.”-False (e.g., Lagos, Nigeria is a megacity but not a global financial hub).
7. “The Rank-Size Rule applies to every country.”-False (works best in developed, balanced economies).

8. “Primate cities are always capital cities.”-False (e.g., Sydney is Australia’s largest city but not the capital—Canberra is).

9. Key Distinctions to Know:

10. Primate City vs. Rank-Size Rule: Primate = one dominant city; Rank-Size = predictable hierarchy.
11. World City vs. Megacity: World city = global influence; Megacity = population size.

12. Forward Capital vs. Primate City: Forward capital = relocated to reduce primacy; Primate city = naturally dominant.

13. Common Themes in FRQs:

14. Uneven development (e.g., “Explain how primate cities contribute to regional inequality”).
15. Urbanization challenges (e.g., “Describe two problems megacities face”).
16. Government policies (e.g., “How can a country reduce urban primacy?”-Build infrastructure in smaller cities, move the capital).

Quick Check Questions

Multiple Choice

1. Which of the following best illustrates the Rank-Size Rule? A) Mexico City (22M) and Guadalajara (5M) B) New York (8.5M) and Los Angeles (4M) C) Tokyo (37M) and Osaka (19M) D) Paris (11M) and Marseille (1.6M) Answer: B. New York and Los Angeles follow the Rank-Size Rule (~2:1 ratio), while the others show primate city patterns.

2. A country with a primate city is most likely to experience: A) Balanced regional development B) Overcrowding and brain drain in smaller cities C) A strong federal government D) High levels of agricultural exports Answer: B. Primate cities concentrate resources, leading to overcrowding and neglect of smaller cities.

Short FRQ

1. The table below shows the populations of the five largest cities in Country X.

A. Does Country X follow the Rank-Size Rule or the Primate City Rule? Explain. B. Describe one economic and one social consequence of this urban pattern.

Answer: A. Primate City Rule. The largest city (15M) is 5x larger than the 2nd city (3M), far exceeding the 2:1 ratio required for primacy. B. Economic: Uneven development—most jobs and investments are in Capital A, leaving smaller cities underfunded. Social: Brain drain—skilled workers migrate to Capital A for opportunities, weakening smaller cities.

Last-Minute Cram Sheet

1. Rank-Size Rule formula: Population of nth city = Largest city population / n.
2. Primate City Rule: Largest city is ?2x the size of the 2nd city.
3. Examples of primate cities: Paris (France), Bangkok (Thailand), Buenos Aires (Argentina).
4. Examples of Rank-Size Rule countries: U.S., Germany, Canada.
5. Megacity = 10M+ people; Metacity = 20M+ people.
6. World cities (global influence): New York, London, Tokyo, Hong Kong.
7. Forward capitals reduce primacy: Brasília (Brazil), Abuja (Nigeria), Canberra (Australia).
8. Gravity Model: Interaction = (Population? × Population?) / Distance².
9. Not all large cities are primate cities—must be 2x larger than the next city.
10. Primate cities-always capitals (e.g., Sydney, Australia).