Ch. 25 Urban Growth
– Urban Area: town or city with more than 2,500 people
-Rural Area: areas with less than 2,500 people
-Degree of urbanization: % of population living in urban areas
-Urban Growth: rate of increase of urban population
1. Between 1950 to 1996 – 200 million to 2.5 billion in urban areas. We are a rapidly
urbanizing World!!
2. The # of mega cities is increasing = 10 million + people.
3. Developing countries have 35% urbanization – projected to be 57% by 2025.
4. Developed countries reach 84% urbanization by 2025.
5. Poverty is becoming more urbanized – slums, barrios, shanty- town. General Trends
in Urbanization.
Causes of Urban Growth
1. Natural increase
2. Immigration
How cities grow
a. Cities have better food supplies, better sanitation, more jobs, more access to
b. Because of mechanized agriculture- fewer rural jobs
c. Government policies in some developing countries distribute most wealth to
the cities where the leader lives.
3. Migration in the U.S.
1ST To cities
2nd cities to suburbs
3rd north & east to south & west
75% live urban – 41% urban
59% suburban
a. U.S. urban problems
- deteriorating services, aging infra structure, poverty, crime, up
b. Good things
- Protect biodiversity by saving land
Major Spatial Patterns
1. Concentric circle city- develops outwards from central business
district- New York
2. Sector City- pie shapes wedges around transportation corridors
3. Multiple- nuclei city - develops around a # of independent centers
*The urban centers are know spreading so much, they are know running into each other
and empty space is disappearing*
Urban Sprawl: dispersed, automobile oriented cities with a low pop. Density which
gobbles up natural habitats.
Environmental Problems associated with cities
No trees, do not produce own food
Water supply problems
Higher concentrations of pollutants
Heat islands
Dust domes
Noise pollution
Loss of land as cities expand
Transportation & Urban Development
- Cars
8% world own cars
1 in 6 Americans employed by car industry
1 in 4 dollars spent on cars
By 1996 had killed 18 million
2,400 a day
Largest source of air pollution
Uses up to ½ of world oil, greenhouse gases
Traffic, noise, stress, costly
By the end of life we spend 2 yrs in the car in U.S.
1/3 urban land for roads & parking
Bicycles & Walking
Cheaper. No pollution
Less danger, Use fewer resources
Lack Of bike Lanes in the U.S.
Rail Systems – rapid rail, light rail, Regional Rail
Pros: More energy efficient, less polluting, fewer injuries, use less land, good for young, old and disabled,
Cheaper per person, cost less than building new highways
Cons: None
High Speed Trains – Bullet, and MAGLEV
Fast and safe
MAGLEV- electromagnetic radiation may be harmful
Pros: more flexible than trains
Less capital, lower operating costs
Cons: cost-effective only when full
can get stuck in traffic
Land Planning
Conventional Land Use Planning: zoning regulations are used to
control land
Money and power struggles
Basis is economic and population growth is encouraged which leads to poorly controlled
2. Ecological Land Use Planning
A. Make a social and economic inventory
B. Identify and prioritize goals
C. Develop maps
D. Develop master composite
E. Develop master plan
F. Implement master plan
G. Not used because it is expensive and elected officials are in
office for only short term and this is a long term commitment
3. Zoning
parcels of land are designated for certain uses only. It is useful but easily influenced by
Making Cities Sustainable
1. energy efficient, lots of walking and biking, mass transit, rapid rail
between cities, recycle, compost, encourage biodiversity.
2. give up big lawns
3. build houses in dense clusters and leave community space
4. develop a town center
5. plant trees
6. discourage dependence on autos

Pros: more flexible than trains Cons: cost