Harold Maclean Lewis Model

– A Conceptual Framework to Understand Urban Growth

Let’s begin with a simple question:
How do we classify cities based on their population?

You might say, “Small town, big town, city, megacity” — but how small is small, and how big is big?

That’s where Harold Maclean Lewis steps in. He gave us a systematic model to classify urban settlements based on population — much like how we classify organisms in biology. His model not only categorizes towns but also helps us understand the stages of urban growth, and how urban centres evolve over time.

Classification of Urban Settlements: A Nine-Tier Typology

Lewis’ model starts at 2,500 people — that’s the minimum population required for a settlement to be considered urban in many parts of the world.

He then classifies urban settlements into nine categories, each reflecting a different stage of urban evolution:

Population Range	Category Name	Meaning
2,500 to 5,000	Eopolis or Infantile Municipality Town	Like an infant town — just beginning to urbanize
5,000 to 10,000	Polis or Juvenile Town	Still growing — youthful stage of a town
10,000 to 25,000	Mature Trade/Industrial Town	Economic activities start becoming visible
25,000 to 50,000	Metropolis or Medium-size City	Urban facilities begin to expand
50,000 to 1,00,000	Megalopolis or Intermediate City	Diverse functions; growing complexity
1,00,000 to 2,50,000	Trade/Industry/Service Sector City	Sectoral specialization begins
2.5 to 5 lakh	Primate City	Dominant city in a region/state
5 to 10 lakh	Tyranopolis or Metropolitan City	Political-administrative and economic hub
10 lakh and above	Senile City or Mega City	Saturated, complex urban system with mega issues

Note: “Senile” here does not mean aged in a negative way — it signifies an advanced stage where growth has slowed, but complexity has peaked.

📊 Understanding Urban Growth Trends

Lewis not only classified cities but also observed how urban growth unfolds over time. He said, we can understand it from two perspectives:

1. Emergence of New Cities over time
2. Growth within existing cities

And based on this framework, we get three historical trends in urban development:

1️⃣ Development of Small and Intermediate Cities (2500 – <1 million)

These are not giant metros, but they fill the gaps — supporting rural areas, easing pressure from big cities, and forming a balanced urban network.

🕰️ When did they grow?

• First phase: After Industrial Revolution till World War I
• Second phase: Post World War II till present

🌐 Why are they important today?

• Decentralization: To shift population and economic load away from overcrowded Primate Cities.
• Better management: Smaller cities are more manageable in terms of planning, services, and security.
• Supportive role: These cities help bridge urban and rural economies — they are the silent warriors of regional development.

2️⃣ Development of Metropolitan Cities (1 million – <10 million)

After World War I, metropolitan cities started dominating. These became the engines of industrialization, administration, and economic activity.

🧭 Characteristics:

• Larger in population
• Economic hubs with manufacturing and administrative functions
• Attract people due to pull factors (jobs, services, better life)
• Also witness push factors from rural areas (poverty, unemployment)

🔄 Post World War II:

Many metropolitan cities transformed into primate cities — large, powerful, dominant urban centres with disproportionate influence on national economies.

3️⃣ Development of Mega Cities (10 million and above)

We now live in the era of Mega Cities — massive urban sprawls like Tokyo, Delhi, Shanghai, etc.

🌍 Global Status:

• Currently, there are about 25 mega cities globally.
• These are not just population centres but also economic powerhouses.

🔄 What drives their growth?

• Population explosion
• Mass migration to urban areas
• Agglomeration economies — cities attract more people as they grow

😓 But with size comes challenges:

• Mega cities are double-edged swords
• They come with Mega economics but also Mega problems:
  Overcrowding, pollution, infrastructure collapse, rising inequality, etc

🎯 Why this Model Matters for UPSC

• It helps us analyze urban trends using a scientific framework.
• Useful in settlement geography and urban planning case studies.
• Explains morphological changes and urban hierarchy.
• Connects historical processes with present-day urban realities.

🧠 Conclusion

Harold Maclean Lewis doesn’t just give us population figures. He gives us a narrative — of how settlements grow, evolve, dominate, and sometimes, collapse under their own weight. From Eopolis to Mega City, it is the story of human civilization told through the lens of urban geography.