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Human Geography · Foundations

Urbanization

9 min read 5 practice questions
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On this page 9 sections
  1. In 30 seconds
  2. Why this matters
  3. The college version
  4. Eli explains
  5. Worked example
  6. Key takeaway
  7. Quick check
  8. Study tools
  9. Sources & references

In 30 seconds

is the process by which a rising share of a population comes to live in cities and towns rather than the countryside. It is measured as the , the percentage of people who are urban. Three forces push that share up: , among city residents, and reclassifying growing rural places as urban. The United Nations reported the world crossed 50 percent urban around 2007-2008 and projected about 68 percent by 2050.

Why this matters

Where people live shapes almost everything geographers study: labor markets, housing, transport, energy use, disease, politics, and the environment. Urbanization is one of the largest transformations in human history, and it is still underway, with nearly all future growth concentrated in Asia and Africa. Understanding the process, and reading its rates correctly, lets you tell a city that is growing because migrants arrive from a city that is growing because it was simply redrawn on a map. It also frames real policy stakes, from housing and clean water to informal settlements, that follow when outpaces the services a city can build.

The college version

What urbanization is, and what it is not

Urbanization is the process by which an increasing share of a population lives in urban areas. The key word is process: urbanization is a rate of change, not a headcount. A useful measure is the level of urbanization, the percentage of a population classified as urban at a given time. A country can add millions of city dwellers and still not be urbanizing if its rural population grows just as fast, because the urban share stays flat. Conversely, a country whose cities barely grow can urbanize rapidly if its countryside empties out. Keep three ideas separate. Urbanization is the rising urban share. Urban growth is the absolute increase in the number of people living in cities. City size is how large a single settlement is. They usually move together, but not always, and confusing them produces bad analysis. One complication runs underneath all of these numbers: there is no single global definition of urban. Each country sets its own threshold, often a minimum settlement population combined with density or economic criteria, so a place counted as urban in one country might be rural in another. That is why cross-country comparisons of urbanization levels must be read with care rather than treated as exact.

What drives it

Three mechanisms raise the urban share. The first is rural-to-urban migration: people move from the countryside to cities, historically drawn by the higher wages and the industrial and service jobs that concentrate in urban economies. This was the engine of urbanization during industrialization and remains powerful in rapidly developing regions today. The second is natural increase, the surplus of births over deaths among people already living in cities; where urban populations are young, cities keep growing even without a single new migrant. The third, easy to overlook, is : as a rural town grows and crosses a country's population or density threshold, it is simply redefined as urban, and its residents shift from the rural column to the urban column without anyone moving at all. Real urban growth blends all three, and their relative weight differs by place and era. In much of today's fastest-urbanizing world, natural increase and reclassification contribute as much as migration, which is why the popular image of urbanization as purely a flood of rural migrants is incomplete. This lesson names migration as a driver and hands its full typology to the migration topic; likewise it treats the economic pull of cities as one force among several rather than the whole story.

The global urban transition

For most of human history the overwhelming majority of people were rural. The urban share of the world's population was on the order of 3 percent in 1800. Industrialization changed that, and the shift accelerated through the 20th century. By the United Nations' World Urbanization Prospects series, the world passed the symbolic halfway mark, more than half of humanity living in urban areas, around 2007-2008, the first time in history that had been true. The UN reported that 55 percent of the world's population was urban in 2018 and projected that share to reach about 68 percent by 2050. In absolute terms the UN projected urban areas could add roughly 2.5 billion people between 2018 and 2050, with close to 90 percent of that increase concentrated in Asia and Africa, and India, China, and Nigeria together accounting for more than a third of it. Every figure here should be stated with its year and attributed to the UN, because these numbers move and because the exact date of the 50 percent crossing depends on how 'urban' is defined. The direction, however, is not in dispute: the human species has become, and is becoming more, an urban one.

Uneven geography, megacities, and strain

Urbanization is not spread evenly across the globe. More-developed regions urbanized early and are already highly urban, on the order of three-quarters of their populations, so their urban share now rises slowly. Less-developed regions started from a lower base but are urbanizing far faster, which is why the frontier of the has moved to Asia and Africa. One vivid feature of that frontier is the , which the UN defines as an urban agglomeration of 10 million or more inhabitants. The UN counted 33 megacities in 2018 and projected 43 by 2030, most of them in the developing world. Megacities capture headlines, but most urban dwellers still live in smaller cities and towns, which is where much of the growth actually lands. Rapid urbanization brings real strain. When people arrive faster than a city can build housing, water, sanitation, and transport, the shortfall shows up as informal settlements, sometimes called slums, and as pressure on basic services. These challenges are not an argument against urbanization, which also concentrates opportunity, innovation, and public services; they are the reason the UN frames managing urban growth as a central sustainable-development task rather than something that takes care of itself.

Eli, the EliExplains learning guide

Eli explains

The same idea, in plain words

Explain it like I’m 10

Imagine a country as a giant classroom split into two groups: kids sitting on the 'farm' rug and kids sitting on the 'city' rug. Urbanization is not about how many kids are in the room. It is about the city rug's share of the class slowly getting bigger year after year. That share can grow three ways: some kids walk over from the farm rug (migration), the city rug's families have new babies (natural increase), or the teacher redraws the line so a corner of the farm rug now counts as city (reclassification). For most of history almost everyone sat on the farm rug. Then, a little after 2007, for the first time ever, more than half the world's people were sitting on the city rug.

Picture it like this

Urbanization is like the water level rising in a tub, not the amount of water. Two tubs can hold the same water, but the one with the narrower rural side has a higher 'urban' level.

Where the picture stops working

The tub image makes urbanization look like a fixed amount of water simply redistributing. In reality the total population is not fixed: cities gain people through births and migration, the countryside can grow too, and the 'line' between rural and urban is redrawn by governments. So the level can rise even while both sides are adding people, which a simple tub cannot show.

Worked example

Suppose a country of 10 million has 4 million urban residents, so its level of urbanization is 40 percent. Over a decade three things happen: 500,000 people move from villages to the capital, urban families have a net natural increase of 300,000, and a growing town of 200,000 crosses the national threshold and is reclassified as urban. Meanwhile the rural areas also grow, ending the decade with the total population at 11 million. The urban count is now 4,000,000 + 500,000 + 300,000 + 200,000 = 5,000,000. The level of urbanization is 5,000,000 / 11,000,000, about 45 percent. The country urbanized, from 40 to 45 percent, and all three drivers contributed, with reclassification alone accounting for a fifth of the urban gain even though not one of those 200,000 people actually moved.

Key takeaway

Urbanization is the rising share of a population that lives in cities, driven by rural-to-urban migration, natural increase, and reclassification. The UN reports the world passed 50 percent urban around 2007-2008 and projects about 68 percent by 2050, with nearly all future growth in Asia and Africa.

Quick check

3 questions here, of 5 in this lesson’s practice set. Answers stay hidden until you check.

Question 1 of 3foundational

In human geography, urbanization is best defined as:

Choose an answer, then check it.
Question 2 of 3intermediate

According to the United Nations' World Urbanization Prospects series, roughly when did the world first become majority urban, with more than half of people living in urban areas?

Choose an answer, then check it.
Question 3 of 3foundational

The United Nations defines a megacity as an urban agglomeration with at least how many inhabitants?

Choose an answer, then check it.
Practice all 5

Keep learning

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Practice this lesson
Study tools & related lessonsYou’ll learn to · Common mistakes · Easily confused · Key vocabulary · Related

You’ll learn to

  • Define urbanization as a process and distinguish it from the size of a city or the total urban population.
  • Explain the three drivers of urbanization: rural-to-urban migration, natural increase, and reclassification.
  • Describe the historic global urban transition using dated figures attributed to the United Nations.
  • Distinguish urbanization in more-developed regions from that in less-developed regions.
  • Apply the concept of a megacity and analyze challenges that follow rapid urbanization.

Common mistakes

  • Treating urbanization as the same thing as a city getting bigger.

    Urbanization is the rising share of a population that is urban. A single city can grow while the country as a whole does not urbanize, if rural areas grow just as fast.

  • Assuming urbanization is caused only by people migrating from farms to cities.

    Migration is one driver. Natural increase among existing city residents and the reclassification of growing towns as urban also raise the urban share, and in fast-growing regions they often matter as much as migration.

  • Stating the year the world became majority urban as an exact, undisputed fact.

    By the UN's World Urbanization Prospects series it was around 2007-2008, but the precise date depends on how each country defines 'urban,' so it should be attributed to the UN and dated, not asserted as a fixed constant.

  • Believing megacities hold most of the world's urban population.

    Megacities (10 million or more) are striking but relatively few; most urban dwellers live in smaller cities and towns, where much of the ongoing growth occurs.

  • Thinking rich countries are still urbanizing fastest because they are the most urban.

    More-developed regions are already highly urbanized, so their share rises slowly; the fastest urbanization now happens in less-developed regions of Asia and Africa.

Easily confused

Urbanization vs. Urban growth

Urbanization is the rising percentage of a population that is urban; urban growth is the absolute increase in the number of urban residents. A country can have rapid urban growth with little urbanization if its rural population grows just as fast.

More-developed regions vs. Less-developed regions

More-developed regions are already highly urbanized (about three-quarters urban) and change slowly; less-developed regions have a lower urban share but are urbanizing much faster and hold most future urban growth.

Rural-to-urban migration vs. Reclassification

Migration raises the urban share by physically moving people into cities; reclassification raises it on paper by redefining a grown-up rural settlement as urban, with no one moving at all.

Key vocabulary

Urbanization
The process by which an increasing share of a population comes to live in urban areas rather than rural ones.
Level of urbanization
The percentage of a population classified as urban at a given time; the standard measure of how urbanized a place is.
Urban growth
The absolute increase in the number of people living in urban areas, which can rise even when the urban share does not.
Rural-to-urban migration
The movement of people from the countryside into cities, historically pulled by urban wages and jobs.
Natural increase
The surplus of births over deaths within a population; among urban residents it raises city populations without any migration.
Reclassification
The redefining of a settlement from rural to urban once it crosses a country's population or density threshold, shifting residents into the urban count without anyone moving.
Megacity
An urban agglomeration with 10 million or more inhabitants, as defined by the United Nations.
Urban transition
The long-run historical shift of a population from majority-rural to majority-urban.
Informal settlement
Housing built outside formal planning and land systems, often lacking secure tenure or full services; commonly called a slum.

Sources & references

  1. 68% of the world population projected to live in urban areas by 2050 (2018 Revision of World Urbanization Prospects) — United Nations Department of Economic and Social Affairs (UN DESA), Population Division
  2. Introduction to Human Geography (Dorrell & Henderson), 12.3: Urbanization — Social Sci LibreTexts / University of North Georgia Press
  3. Urbanization — Our World in Data (Hannah Ritchie, Veronika Samborska, Max Roser)

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Researched 2026-08-19

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