Urbanization refers to the increasing share of a nation's population living in urban areas and the decline of rural populations. The document discusses the history and trends of urbanization in the United States and globally. It notes that urbanization began in the US along the eastern seaboard in the late 18th century and accelerated in the 19th century due to immigration and industrialization. Today, over half the world's population lives in urban areas, with many megacities emerging. Urbanization impacts the atmosphere, lithosphere, hydrosphere, and biosphere through increased pollution, habitat destruction, and changes to land, air, water, and ecosystems.

3. •Urbanization is the increase over time in the population of cities in relation to
the region's rural population.(new world encyclopedia)
•The increasing share of a nation's population living in urban areas (and thus a
declining share living in rural areas).
•The term urbanization is also used for the expansion of urban land uses.
•It moves populations from traditional rural environments with informal
•political and economic institutions to the relative anonymity and more formal
•institutions of urban settings.

4. •Urbanisation was first started in United States of America
•During the American colonial period, cities along the eastern seaboard were the
centers of commerce and politics, thus urbanization began there
• Boston, New York, and Philadelphia were the three largest cities in population size.
Yet they were tiny in comparison to their size today. In 1790, the year after George
Washington became the first president of the new nation, New York’s population
was only 33,131; Philadelphia’s was 28,522; and Boston’s was 18,230 .
•Today, of course, cities of this size are called small towns. New York’s population is
vastly higher, at about 8.2 million; Philadelphia’s is 1.5 million; and Boston’s is 618,
000.

5. • US cities became more numerous and much larger during the
nineteenth century because of two trends.
• The first was immigration, as waves of immigrants from Ireland and
then Italy and other nations began coming to the United States
during the 1820s.
•The second was industrialization, as people moved to live near
factories and other sites of industrial production.
• These two trends were momentous: People crowded together as
never before, and they crowded into living conditions that were
often squalid.
•American cities grew even more rapidly after the Civil War as both
industrialization and immigration continued. By the early years of
the twentieth century, US cities on the East Coast were almost
unimaginably crowded

6. Global Urbanization
•If the United States has urbanized during the last two centuries, so has
much of the rest of the world.
•Only 3 percent of the world’s population lived in urban areas in 1800.
• By a century later in 1900, 14 percent of the world’s population lived in
urban areas, and twelve cities had populations over 1 million.
•Just a half-century later in 1950, the world’s urban population had
doubled to 30 percent, and the number of cities over 1 million grew six
times to eighty-three cities.
•Today, more than half the world’s population lives in urban areas, and
the number of cities over 1 million stands at more than four hundred.
•By 2030, almost two-thirds of the world’s population is projected to live
in urban areas.
•The number of megacities—cities with populations over 10 million—
rose from three in 1975 to sixteen in 2000, and is expected to reach
twenty-seven by 2025

9. •Spread of education
•Modernization
•Change in Dress habits.
•Adoption of modern Technology
•Enlightenment of women.
•Modern transport and communication. E.g.: Cell phones
have become common even among rural people.
•Active involvement in politics.
•Growth of infrastructure like Banks, Post office.
•Awareness among rural consumers.
• Increasing demand for sophisticated products like
cosmetics etc.

10. [A] IMPACTS ON THE ATMOSPHERE AND CLIMATE
1. The creation of heat island
Materials like concrete, asphalt, bricks etc absorb and reflect energy differently than vegetation
and soil.
Cities remain warm in the night when the countryside has already cooled.
2.Changes in Air Quality
Human activities release a wide range of emissions into the environment including carbon
dioxide, carbon monoxide, ozone, sulfur oxides, nitrogen oxides, lead, and many other
pollutants.
3. Changes in Patterns of Precipitation
Cities often receive morerain than the surrounding countryside since dust can provoke the
condensation of water vapor into rain droplets.

11. [B] IMPACTS ON THE LITHOSPHERE AND LAND RESOURCES
1. Erosion and other changes in land quality
Rapid development can result in very high levels of erosion and sedimentation in river
channels.
2. Pollution
Pollutants are often dispersed across cities or concentrated in industrial areas or waste
sites. Lead-based paint used on roads and highways and on buildings is one such
example of a widely dispersed pollutant that found its way into soil. Burying
tremendous amounts of waste in the ground at municipal and industrial dumps

12. [C] IMPACTS ON THE HYDROSPHERE AND WATER RESOURCES
1. Flow of Water into Streams
Natural vegetation and undisturbed
soil are replaced with concrete, asphalt, brick, and other
impermeable surfaces. This means that, when it rains, water is less likely to be
absorbed into the ground and, instead, flows directly into river channels.
2.Flow of Water through Streams
Higher, faster peak flows change streams channels that have evolved over centuries under
natural conditions.
Flooding can be a major problem as cities grow and stream channels attempt to keep up with
these changes.
3. Degraded Water Quality
The water quality has degraded with time due to urbanization that ultimately leads to increased
sedimentation there by also increasing the pollutant in run-off.

13. D] IMPACTS ON THE BIOSPHERE
1. Modification of Habitats
The fertilizers that spread across lawns finds its way into water channels where it promotes the
growth of plants at the expense of fish.
The waste dumped into streams lowers oxygen levels during its decay and cause the die-off of
plants and animals.
2. Destruction of Habitats
There is also complete eradication of habitats as an outcome of Urbanization and native species
are pushed out of cities.
3. Creation of New Habitats
New habitats are also created for some native and non-native species.
Cities also create habitats for some species considered pests, such as pigeons, sparrows, rats,
mice, flies and mosquitoes.
Urbanization has, for example, eliminated many bat colonies in caves, but has provided sites
such as bridges for these species to nest.

16. Census 2011: Tamil Nadu 3rd most urbanized state
CHENNAI: More people in Tamil Nadu have moved from rural to urban areas the last 10
years compared to other states, according to the 2011 Census data. Tamil Nadu tops the
list of urbanised states with 48.45% of its population living in urban areas , followed by
Kerala, Maharashtra and Gujarat.
In the last 20 years, the rate of urbanization in Tamil Nadu has been rapid. According to
the 1991 Census, only 34.15% of the total population in Tamil Nadu was classified as
urban but in 2011, it has risen to 48.45%, an increase of 14.3%. Since the 2001 census,
the percentage of urban population has risen by 4.41%.
"In Tamil Nadu, between 1991 and 1996 many rural areas have been reclassified as
urban after the 74th amendment to the Constitution . This could be one reason for
more people now living in urban areas," said Karen Coelho, assistant professor, Madras
Institute of Development Studies, who specialises in urban anthropology.

25. •Urbanization is referred to as “necessary evil”
•Instead of migrating to cities, developing the rural areas is a
better option
•Increase the educational and job facilities in rural areas
•At least the rate of migration should b reduced
•Recycling of all non renewable resources have to be encouraged
to meet the increasing demand
•The clearing of many slums and a huge increase in adequate
housing for low-income individuals