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READ: Data Exploration - Urbanization

Most humans live in cities today. Yet for most of our history, this was not the case. The shift to cities is a long story, but it’s one that accelerated quite recently.
The data exploration article below uses “Three Close Reads”. If you want to learn more about this strategy, click here.

First read: preview – what do we have?

This will be your quickest read. It should help you get the general idea of what this chart is about and the information it contains. Pay attention to:
  • Labels and titles. What is the title? How are the axes labeled? Is anything else on the chart labeled?
  • Data representation. How many variables are there and what are they? What are the scales? What time period does the chart cover? Is the chart interactive?
  • Data source. Where did the data for this chart come from? Do you trust it? Who created the chart?

Second read: key ideas – what do we know?

In this read, you will pay attention to the information that most helps you understand the chart and the information it is trying to convey. Pay attention to:
  • Claim(s). What can you say about the data? What story does it tell? Can you make any claims about this data? Does it change when you zoom in compared to when you look at the data as a whole?
  • Evidence. What data from the chart supports this story? Does this change if you change the scale or variables?
  • Presentation. How does the way this chart is presented influence how you read it? Has the author selected certain variables or scales that change the conclusions that can be drawn? Is there anything missing from this chart?
By the end of the second read, you should be able to answer the following questions:
  1. How has urbanization changed in the last 12,000 years?
  2. How are Charts 1 and 2 different?
  3. What does Chart 3 tell us about the impacts of urbanization on human use of the land?
  4. What does Chart 4 suggest about the relationship between urbanization and wealth?
  5. Thinking back to the “ice cream and violent crime” chart from “A Guide to Reading Charts,” can you think of any problems with Chart 4? Can you think of any other variables (like weather in the ice cream chart) that might explain both high levels of urbanization and wealth?

Third read: making connections – what does this tell us?

The third reading is really about why the chart is important and what it can tell us about the past and help us think about the future. Pay attention to:
  • Significance. Why does this matter? Does this impact me, and if so, how? How does it connect what is going on in the world right now? How does it relate to what was happening at the time it was created?
  • Back to the future. How does this data compare to today? Based on what you now know, what are your thoughts on this phenomenon 25 years, 50 years, and 100 years from now?
At the end of the third read, you should be able to respond to these questions:
  1. What are the connections between these four charts? Together, what do they tell us about urbanization in the long term of human history? What do they tell us about the more recent past?
  2. Using these four charts, make one prediction about how urbanization will change in your lifetime. What evidence from the charts supports your prediction? What evidence challenges it?
Now that you know what to look for, it’s time to read! Remember to return to these questions once you’ve finished reading.

Urbanization Data Introduction

Aerial view of a major city with many skyscrapers close together.
By Max Roser, adapted by Mike Papritz and Bennett Sherry
Most humans live in cities today. Yet for most of our history, this was not the case. The shift to cities is a long story, but it’s one that accelerated quite recently.


Human population began its slow pace of growth many thousands of years ago. As agriculture developed, human populations grew denser—more of us lived closer to each other in less space. Humans started settling in permanent farming villages. Eventually, population density increased even further in some places, leading to the development of a new type of human community: the city.
For most of the last 6,000 years, the number of cities and the number of humans living in cities has increased steadily. Over our very long history, a greater and greater percentage of the human population moved to cities, a trend we call urbanization. But still, for most of human history, the majority of people did not live in cities. Before 1600 CE, less than 5 percent of people lived in cities. By 1800, this share reached 7 percent, and by 1900, it had increased to 16 percent. In the past century, this trend has only accelerated. Today, over half of the 7 billion humans on Earth live in cities.

What is a city?

There's no agreement on what defines a city. Different people define a city in different ways. And for many scholars, what constituted a city in 200 BCE was smaller than the minimum size of a city in 2000 CE. Chart 1 shows the size of urban areas in several different countries and regions since 10,000 BCE. Of course, for most of that time, no one lived in cities. But starting around 3700 BCE, the first cities developed. Zooming in to a smaller scale of time in Chart 2, you can see just how recently urbanization took off.
Chart 1:
Graph showing estimated urban area by region or country, measured in square kilometers, from 10,000 BCE to 2000. The graph indicates that estimated urban area remained below 10,000 square km for 10,000 years until the year 2000 when there was a sharp increase, reaching over 80,000 square km in Western Europe and 140,000 square km in the United States.
Urban area over the long-term: https://ourworldindata.org/grapher/urban-area-long-term By Our World in Data, CC BY 4.0.
Chart 2:
Chart measuring the total population living in urban areas at different times from 1500 to 2016, showing a sharp increase from 1800 to 2016.
Urbanization over the past 500 years https://ourworldindata.org/grapher/urbanization-last-500-years By Our World in Data, CC BY 4.0.
These charts make it look like cities cover the entire world. But if we look closer at the data, we see that's not true. Cities have always depended on the labor of people outside of cities—farmers and herders. About 71 percent of the Earth's land is habitable (suitable for human life). Today, we use about half of that for agriculture. Chart 3 shows how humans have used land over the last two millennia (note that ha is an abbreviation for hectare; one hectare is about two and a half acres). Our "built environment"—cities, towns, roads, and other infrastructure—has increased substantially in the past century, but it still only accounts for 1 percent of the Earth's habitable land. Despite the relatively small percentage of Earth's surface covered by cities, if you compare the rise in agricultural land use in the last 200 years to urbanization, you can see that cities have an impact that stretches beyond their ZIP codes.
Chart 3:
Graph showing total land area used for cropland, grazing land, and built-up areas (villages, cities, towns, and human infrastructure), measured in hectares (ha). Land use slowly increased from the year 100 to the year 1000 with a sharp increase in use occurring around the year 1800.
Land use over the long-term: https://ourworldindata.org/grapher/land-use-over-the-long-term By Our World in Data, CC BY 4.0.

Urban consequences

What are the consequences of living in more densely populated areas? Are there things people living in cities, even cities small by today's standards, must do to live so close to so many others? For example, do people create new jobs to manage larger populations of strangers? What problems might emerge living in closer proximity to others? What might be the benefits? Are there activities—such as farming—that city dwellers are unlikely to do and must then depend on others from outside the city doing? Some historians argue that when earlier humans transitioned from hunter-gatherer lifestyles to farming, the lives of many became more difficult. But what about cities? Ancient cities were often dirty places that put people at risk of disease. Why did so many people choose to live in crowded, complicated cities?
One answer might be that cities provide new opportunities and wealth. Chart 4 shows the relationship between gross domestic product (GDP)—a measurement of a nation's economic production—and the percentage of people who live in cities in that country. Over the past 500 years, there has been a strong correlation between the percentage of people in a country living in cities and how wealthy that country is. It appears that populations urbanize as they get richer, or, perhaps, they get richer as they urbanize.
The causes and effects of urbanization are complex, and our data for humanity's long history is incomplete. However, we know that living in cities has historically had lots of advantages. Some advantages include high levels of concentrated economic activity, access to trade, the availability of more human labor, shared infrastructure like walls and granaries, and a division of labor that means not everyone has to farm. For the last 6,000 years, more and more people have built and moved to cities to try and have access to these advantages.
Chart 4:
Chart comparing the share of the total population living in urban areas to the gross domestic product per capita from 1500 to 2016.
Urban population vs. GDP: https://ourworldindata.org/grapher/urbanization-vs-gdp?time=1500..latest By Our World in Data, CC BY 4.0.
Do you think global urban population always grew? What might be the causes of historical changes in urban population? Why did early cities develop where they did? How did urbanization change human societies? How did it change our planet? What parts of the world and what types of people have benefited most from urbanization?
Author Bio
Max is the founder and director of Our World in Data. He began the project in 2011 and for several years was the sole author, until receiving funding for the formation of a team. Max’s research focuses on poverty, global health, and the distribution of incomes. He is also Programme Director of the Oxford Martin Programme on Global Development at the University of Oxford, and Co-executive Director of Global Change Data Lab, the non-profit organization that publishes and maintains the website and the data tools that make OWID’s work possible.

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