Concept Notes 1: Urban Transformation: Megacities, Tier-2 Growth & Rural-to-Urban Shift
Urbanization is the process by which an increasing proportion of a country's population comes to live in cities and towns, accompanied by structural shifts from agrarian livelihoods to manufacturing, trade, and services.

1. Census Definition of an Urban Settlement in India
The Census of India classifies urban areas into two statutory categories:
- Statutory Towns: All administrative places with a municipality, municipal corporation, cantonment board, or notified town area committee established by law.
- Census Towns: Places that satisfy all three of the following demographic conditions:
- A minimum total population of 5,000 persons.
- At least 75% of the male main working population engaged in non-agricultural pursuits.
- A population density of at least 400 persons per square kilometer (1,000 per sq mile).
2. Historical Trajectory of Urban Growth in India
URBAN POPULATION SHARE (%) IN INDIA (1901โ2024)
40% โโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโ (35%+)
30% โโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโ (27.8%)
20% โโโโโโโโโโโโโโโโโโโโโโโโโโโโ (17.3%)
10% โโโโโโโโโโโโ (10.8%)
0% โโโโฌโโโโโโโโโโโโฌโโโโโโโโโโโโโโโฌโโโโโโโโโโโโโโโฌโโโโโโโโโโโโโโโฌโโโ
1901 1951 1971 2001 2024
- Colonial Era (Pre-1947): Urbanization was slow and focused on export-oriented port cities established by the British (the Presidency capitals: Calcutta, Bombay, Madras) and military cantonments.
- Post-Independence Industrialization (1951โ1991): Public-sector industrial townships emerged around heavy steel and mineral centers (Bhilai, Rourkela, Durgapur, Jamshedpur).
- Post-1991 Economic Liberalization: Driven by service sectors, IT corridors, telecommunications, and finance, leading to the rapid expansion of megacities and surrounding satellite suburbs (Gurugram, Noida, Navi Mumbai, Cyberabad).
3. Classification of Indian Cities by Size
- Class I Cities: Urban settlements with a population of 100,000 (1 Lakh) or more.
- Metropolitan Cities (Million-Plus Cities): Urban centers with a population exceeding 1 Million (10 Lakhs). In 2011, India had 53 million-plus cities.
- Megacities: Urban agglomerations with a population exceeding 10 Million (1 Crore):
- Greater Mumbai Urban Agglomeration (~21 Million)
- Delhi National Capital Region (NCR) (~30 Million)
- Kolkata Urban Agglomeration (~15 Million)
- The Rise of Tier-2 and Tier-3 Hubs: Medium-sized cities like Pune, Ahmedabad, Surat, Jaipur, Kochi, Indore, and Coimbatore are expanding at faster annual percentage rates than older megacities, acting as decentralized engines of regional employment.