How has urbanization affected population distribution in the united states?
More than half of the world’s population now live in urban areas — increasingly in highly-dense cities. However, urban settings are a relatively new phenomenon in human history. This transition has transformed the way we live, work, travel and build networks. Show
This entry presents an overview of urbanization across the world, extending from the distant past, to present, and projections of future trends. Summary
All our interactive charts on Urbanization
Chart 1 of 30 Urbanization across the world todayIn this section
Number of people living in urban areasMore than 4 billion people – more than half of the world – live in urban areasFor most of human history, most people across the world lived in small communities. Over the past few centuries – and particularly in recent decades – this has shifted dramatically. There has been a mass migration of populations from rural to urban areas. How many people live in urban areas today? In the visualization, we see estimates from the UN World Urbanization Prospects on the number of people globally who live in urban and rural areas. More than 4.3 billion people now live in urban areas. This means over half of the world (55% in 2017) live in urban settings. The UN estimates this milestone event – when the number of people in urban areas overtook the number in rural settings – occurred in 2007. You can explore the data on urban and rural populations for any country or region using the “change country” toggle on the interactive chart. Click to open interactive version Share of populations living in urban areasHow does the share of people living in urban areas vary between countries? In the map shown here, we see the share of the population that is urbanized across the world. Across most high-income countries – across Western Europe, the Americas, Australia, Japan and the Middle East – more than 80% of the population live in urban areas. Across most upper-middle-income countries – in Eastern Europe, East Asia, North and Southern Africa, and South America – between 50% to 80% of people do. In many low to lower-middle-income countries, the majority still live in rural areas. But this is changing quickly. By clicking on any country you can see how urbanization rates are changing with time. For many countries, you see a rapid migration of populations into towns and cities. Click to open interactive version How urban is the world?What we know about urban populations and why it mattersBefore looking in more detail at the differences in estimates of urban populations, we should first clarify what we do know:
Whilst disagreement on the numbers can seem irrelevant, understanding cities, urbanization rates, the distribution, and the density of people matters. The allocation and distribution of resources — ranging from housing and transport access to healthcare, education, and employment opportunities — should all be dependent on where people live. Understanding the distribution of people in a given country is essential to make sure the appropriate resources and services are available where they’re needed. The UN’s 11th Sustainable Development Goal (SDG) is to “make cities inclusive, safe, resilient and sustainable“. If our aim is to develop resource-efficient, inclusive cities, understanding how many people they must provide for is essential for urban planning. Let’s, therefore, look at the conflicting estimates of how urban our world is, and where these differences come from. UN estimates: 55% of people live in urban areasAt first glance, this seems like a simple question to answer. Figures reported from the United Nations (UN) deliver a straightforward answer.3 In the chart here we see the total number of people defined as living in urban and rural areas, extending from 1960 to 2020.4 This is based on nationally-collated census figures, combined with UN estimates where census data is unavailable. Here we see that in 1960 twice as many people lived in rural settings (2 billion) than in urban areas (1 billion). In 2007, urban and rural populations were almost exactly equal at 3.33 billion each. In 2016, urban populations increased to 4.4 billion; while the world’s rural population had increased only marginally to 3.4 billion. The UN figures are the most widely referenced and cited on global urbanization. However, they’re not without their critics: some researchers suggest that far more people live in urban areas than these figures suggest. Why are they so contested? Click to open interactive version How is an urban area defined?‘What defines an urban area?’ lies at the center of these debates. There is currently no universal definition of what ‘urban’ means. The UN reports figures based on nationally-defined urban shares. The problem, however, is that countries adopt very different definitions of urbanization. Not only do the thresholds of urban versus rural vary, but the types of metrics used also differ. Some countries use minimum population thresholds, others use population density, infrastructure development, employment type, or simply the population of pre-defined cities. In the table, we highlight the varied definitions across a selection of countries. The UN World Urbanization Prospects database also provides the full downloadable list of statistical definitions for each country. The table illustrates the broad range of definitions between countries which compromises cross-country comparisons. And since the reported global figure is simply the sum of nationally-reported shares, the lack of a universal definition is also problematic for these aggregated figures. Even if we could define a single metric to use — such as a minimum population threshold in a settlement — countries adopt very different thresholds. In the chart here we have mapped the minimum population threshold for countries who adopt this within their definition of ‘urban’. 2000 and 5000 inhabitants were jointly the most frequently-adopted threshold. However, the variation across countries was vast. Sweden and Denmark set this threshold at only 200 inhabitants; Japan at 50,000 (a 250-fold difference). National definitions of ‘urban area’ as used for a custom selection of countries5 CountryNational definition of 'urban'ArgentinaLocalities with 2,000 inhabitants or more.SwedenBuilt-up areas with 200 inhabitants or more and where houses are at most 200 metres apart.JapanCities defined as shi. In general, shi refers to a municipality that satisfies the following conditions: (1) 50,000 inhabitants or more; (2) 60 per cent or more of the houses located in the main built-up areas; (3) 60 per cent or more of the population (including their dependents) engaged in manufacturing, trade or other urban type of business.IndiaStatutory places with a municipality, corporation, cantonment board or notified town area committee and places satisfying all of the following three criteria: (1) 5,000 inhabitants or more; (2) at least 75 per cent of male working population engaged in non-agricultural pursuits; and (3) at least 400 inhabitants per square kilometre.ZimbabwePlaces officially designated as urban, as well as places with 2,500 inhabitants or more whose population resides in a compact settlement pattern and where more than 50 per cent of the employed persons are engaged in non-agricultural occupations.SingaporeEntire population.UruguayCities officially designated as such. Click to open interactive version European Commission estimates: 85% of people live in urban areasCritics of current UN figures, therefore, say that such varied definitions of ‘urban’ lead to a significant underestimation of the world’s urban population. Researchers from the European Commission, for example, reported that 85% of people live in urban areas.6 Its project, Atlas of the Human Planet, combines high-resolution satellite imagery with national census data to derive its estimates of urban and rural settlements. The European Commission applied a universal definition of settlements across all countries:
Using these definitions, it reports that 52% of the world lived in urban centers, 33% in urban clusters, and 15% in rural areas in 2015. This makes the total urban share 85% (more than 6.1 billion people). The reported urban share by continent is shown in the chart here. The European Commission’s estimates are also not without its critics. Researchers at the Marron Institute of Urban Management (New York University) challenged these figures as a gross overestimation.7 The authors suggest multiple reasons why such figures are too high: based on agricultural employment figures, they estimate urban populations cannot exceed 60%; the low urban-density threshold adopted by the European Commission means entire cropland regions are classified as urban; and that this low-density threshold is inconsistent with observed population densities on the fringes of cities. Click to open interactive version Will we ever reach a consensus on urban population?Clearly how we define an urban area has a significant impact on its estimated population. UN figures report 4 billion, whilst the European Commission reports 6 billion (a difference of one-third). While there are clear differences in estimates at the global level, the overall trend in urbanization at national levels (regardless of their definition) is still important. It’s vital for India, for example, to know that from 1990 to 2016, its urban population increased by 148 million (increasing from every 4th to every 3rd person). The rate of this change is important for its evaluation of progress, demographic change, and national planning. The lack of consensus on figures at the global level therefore shouldn’t overshadow what they represent at national levels. But would the world adopt a standardized definition? The UN Statistics Division has convened multiple expert groups in recent years to try to work towards a common definition, but none have been successful. With such a wide array of national definitions, achieving this would be a difficult task. Countries have the right to define what they consider to be urban and rural settlements. One proposed option is to maintain individual definitions for national figures but to adopt a new universal definition for estimating the global and/or regional share. This may, at least, bring us one step closer to an agreement on how urban the world really is. Urban slum populationsIn this section
Share of people living in slumsJust under 1-in-3 urban dwellers live in slum householdsQuality of living standards in urban centers is of course an important measure of wellbeing. One metric of living standards is the share of the urban population living in slum households. A slum household is defined as a group of individuals living under the same roof lacking one or more of the following conditions: access to improved water, access to improved sanitation, sufficient living area, and durability of housing. The most recent global estimates suggest just under 1-in-3 people in urban areas lived in slum households. The share of the urban population living in slums by country is shown in the chart. This data is available from the year 1990. Here we see that in the latest data, most countries across Asia and Latin America had between 10 to 30% of urban populations living in slum households (some slightly higher). Slum households were most prevalent across Sub-Saharan Africa; most had more than half of urban populations living in slum households, and some (such as Sudan, South Sudan, and the Central African Republic) had more than 90%. We see that over time, for most countries, the share of the urban population living in slums has been falling. From 1990 to 2014, for example, the share of the urban population in slum households fell from:
Click to open interactive version Numbers living in urban slumsHow many people are living in urban slums? In the chart, we see the total number of people living in urban slum households, and the urban population not living in slums. This is available to view by country using the “change country” option in the top-left of the chart. Here we see that despite continued population growth and urbanization rates across most countries, the absolute number of people living in urban slum households has also been falling across many countries. A map of total number of people living in urban slum households by country is available to explore here. Click to open interactive version Urban densityUrban agglomerationsAlthough the definition of ‘urban’ gives us some indication of population densities, it does not differentiate between those that live in small versus large urban settings. In the chart, we show the percentage of the total population that lives in agglomerations greater than one million people (i.e. large urban agglomerations). These figures are available in absolute terms (the total number of people living in large urban settings), found here. Here we see large differences across the world. Smaller city-based nations such as Kuwait, UAE, Japan, Puerto Rico and Israel tend to have high rates of large urban agglomeration: more than half live in large cities. Across much of the Americas, 40 to 50% live in large urban agglomerations. Most other countries across Europe, Asia, and Africa lie somewhere in the range of 10 to 40%. There are a few countries that have a very low prevalence of large cities — in Germany and the Netherlands, for example, less than 10% of the population live in cities over 1 million despite having large urbanization rates. Click to open interactive version Population in largest cityWe can also look at this centralisation effect through the share of the urban population which lives in the single largest city. This is shown in this chart. Here we have a handful of countries — such as Mongolia, Paraguay, Uruguay, Liberia, Senegal and Afghanistan — where more than half of the country’s urban population live in its largest city. Overall, this share tends to be higher in countries across Africa and Latin America; a share of 30 to 50% is common. Rates across Europe, Asia, and North America are highly variable, ranging from over 40% to less than 10%. Click to open interactive version City populationsPopulation of the capital cityIn the chart we see the world mapped based on the population of each country’s capital city. In 2018, Japan’s capital — Tokyo — had the largest population of the world’s capital cities at over 37 million people. This was followed by Delhi (India) at over 28 million; Mexico City (Mexico) at 21 million; and Cairo (Egypt) with 20 million. Across the world, the most common capital size was in the range of 1 to 5 million people. Click to open interactive version Population of citiesMany cities across the world have grown rapidly over the past 50 years in terms of their total population. The chart shows the estimated population of the world’s 30 largest cities (by 2015 population) from 1950 to 2015, with projections through to 2035.8 Beijing in 1950, for example, had a population of 1.7 million. By 2015 this was more than 10 times higher, at more than 18 million. By 2035 it’s expected this will increase further to 25 million. Dhaka (capital of Bangladesh) increased from less than half a million in 1950 to almost 18 million in 2015 (and projected to reach 31 million by 2030). Using the “change city” in the top-left of the chart, you can browse trends for the largest 30 cities.
Click to open interactive version Long-run history of urbanizationIn this section
Urbanization over the past 500 yearsMigration to towns and cities is very recent – mostly limited to the past 200 yearsHow has urbanization changed over longer timescales – over the past 500 years? In the map here we see how the share of populations living in urban areas has changed in recent centuries. Data on urbanization dating back to 1500 is available only for select countries, with an estimated share at the global level. Using the timeline on the map (or by clicking on a country) you can see how this share has changed over time. Here we see clearly again that urbanization has largely been confined to the past 200 years. By 1800, still, over 90% of the global (and country-level) population lived in rural areas. Urbanization in the United States began to increase rapidly through the 19th century, reaching 40% by 1900.9 By 1950 this reached 64% and nearly 80% by 2000. This rate of urbanization was, however, outpaced by Japan. Urban shares in Japan were low until the 20th century.10 By 1900, it had just surpassed 1-in-10. This increased rapidly, reaching over half of the population by 1950; nearly 80% by 2000, and surpassing the USA to over 90% today. China and India had similar rates of urbanization until the late 1980s.11 By then, both had around 1-in-4 living in urban areas. However, China’s rate of urbanization increased rapidly over the 1990s and 2000s. Over this 30-year period, its urban share more than doubled to 58%. India’s rise has continued to steadily rise to 1-in-3 (33%) today. Click to open interactive version Urbanization over the past 12,000 yearsThe recency of urbanization becomes even more pronounced when we look at trends for countries and regions over even longer timescales – the past 10,000 years. This is shown in the visualization here, derived from the work of the History Database of the Global Environment.12
Click to open interactive version Future urbanizationIn this section
What share of people will live in urban areas in the future?By 2050, more than two-thirds of the world will live in urban areasThe past 50 years in particular have seen a rapid increase in rates of urbanization across the world. Are these trends likely to continue? The UN World Urbanization Prospects provide estimates of urban shares across the world through to 2050. These projections are shown in the chart — using the timeline you can watch this change over time. Across all countries, urban shares are projected to increase in the coming decades, although at varied rates. By 2050, it’s projected that 68% of the world’s population will live in urban areas (an increase from 54% in 2016). In fact, by 2050 there are very few countries where rural shares are expected to be higher than urban. These include several across Sub-Saharan Africa, Asia, Pacific Island States, and Guyana in Latin America. Why, when most countries are expected to be mostly urban, is the global total just over two-thirds? This seems low but results from the fact that many of the world’s most populated countries have comparably low urban shares (either just over half or less). For example, India (expected to be the world’s most populous country), is projected to have an urban share of only 53% in 2050. The other map shown here provides a snapshot overview of how the world is expected to continue to become more urbanized. It shows, for any given country, whether more people (the majority) live in urban or rural areas. Click to open interactive version Click to open interactive version How many people will live in urban areas in the future?By 2050, close to 7 billion people are projected to live in urban areasIn the chart we see estimates of urban and rural populations in absolute terms, projected through to 2050. Projected population growth based on the UN’s medium fertility scenario. As of 2018 we see that there is around 7.6 billion people in the world (4.2 billion in urban and 3.4 billion in rural areas). By 2050, global population is projected to increase to around 9.8 billion. It’s estimated that more than twice as many people in the world will be living in urban (6.7 billion) than in rural settings (3.1 billion). These trends can be explored by country or region using the “change country” function in the top-left of the chart. Using our timeline map of urbanization you can explore how countries are expected to transition from predominantly rural to urban in the coming decades. There we see that by 2050 it’s projected that the majority of countries will have a majority (greater than 50%) of people living in urban areas. Click to open interactive version How do living standards change as people move to urban areas?In this section
Populations urbanize as they get richerIn the chart, we show the relationship between the share of the population living in urban areas on the y-axis, and average income (gross domestic product per capita) on the x-axis. Here we see a strong relationship between urbanization and income: as countries get richer, they tend to become more urbanized. The link between urbanization and economic growth has been well documented.13,14,15 Urbanization is complex, however: there are many recognized benefits of urban settings (when developed successfully) including high-density of economic activity, shorter trade links, utilization of human capital, shared infrastructure, and division of labor.16,17,18 Is there causal feedback by which urbanization is also a predictor of future economic growth? The evidence for this is relatively weak — assessments of this effect suggest that countries with a higher initial urban population share do not achieve faster or slower economic growth than countries with a low initial urban population share.19 Click to open interactive version Urban populations tend to have higher living standardsThere are many examples — across broad areas of development — which suggest that, on average, living standards are higher in urban populations than in rural. Some examples include:
Note, however, that it is difficult to infer causality between urbanization and these examples. Since urbanization shows a strong correlation with income, such relationships may instead simply show the effect of higher incomes on electricity access, sanitation, drinking water and nutrition. Furthermore, there can also be significant inequalities within urban areas; this is evidenced by the fact that across many low-to-middle income countries a high share of the urban population live in slum households (which lack access to all of the basic resources). Agricultural employment falls with urbanizationIt would be expected that changing where populations live will have an impact on types of employment. Rural-urban migration has been empirically linked with the structural transformation process: as urban population shares increase, employment tends to shift from agriculture towards industry/manufacturing, or services.20 In the chart, we see the share of people employed who are in agriculture (y-axis) versus the share of the population living in urban areas (x-axis). Here, in general, we see that agricultural employment tends to decline with urbanization. In our blog post ‘Structural transformation: how did today’s rich countries become deindustrialized?’ we discuss and look at the data on this agriculture-industry-services shift in more detail. Although this agriculture-urbanization link tends to hold true for most countries, there are a couple of clear outliers. Sri Lanka, Samoa, and Barbados, for example, appear to show relatively low levels of agricultural employment despite being predominantly rural. For Sri Lanka, this anomaly is explained by low urbanization rates, rather than relatively low levels of agricultural employment — a labor share of just under 30% in agriculture is similar to neighboring countries in the Asia-Pacific region. In the case of Barbados and Saint Lucia, low agricultural production and employment are common for many small island states. Click to open interactive version Definitions & MeasurementIn this section
How is an urban population defined?There is no universal definition of what constitutes an ‘urban area’. Definitions of an urban settlement vary widely across countries, both in terms of the metrics used to define them, and their threshold level. The UN World Urbanization Prospects (2018) database provides a downloadable list of underlying data sources and the statistical concepts used to define ‘urban’ by country.21 In the chart we have mapped the minimum threshold level of the number of inhabitants in a settlement needed for it to be classified as an ‘urban area’. The data shown for a given country is its nationally-defined minimum threshold. When we look at the frequency at which a given threshold level is used by a country, we see that 2000 and 5000 inhabitants are the most frequently adopted (by 23 countries each). However, these ranges vary widely: Sweden and Denmark, for example, use a threshold of only 200 inhabitants whereas Japan adopts a very high threshold of 50,000 inhabitants. Note that 133 countries do not use a minimum settlement population threshold in their ‘urban’ definition. Some use a variation of population density, infrastructure development, pre-assigned city populations, or in some cases no clear definition. The UN adopts national definitions in its reporting of urban versus rural populations. This means urban populations are often not comparable across countries. Global urbanization trends also encounter this issue: world urban population is reported as the sum of nationally-defined urban populations (therefore summing metrics/thresholds which are not directly comparable). Click to open interactive version How is a slum household defined?UN-HABITAT defines a slum household as a group of individuals living under the same roof in an urban area who lack one or more of the following22: 1. Durable housing of a permanent nature that protects against extreme climate conditions. 2. Sufficient living space which means no more than three people sharing the same room. 3. Easy access to safe water in sufficient amounts at an affordable price. 4. Access to adequate sanitation in the form of a private or public toilet shared by a reasonable number of people. Sometimes a fifth criterion is included: 5. Security of tenure that prevents forced evictions. It should be noted that although a single categorisation of a ‘slum household’ is given, the conditions and level of deprivation can vary significantly between slum households. Some households may lack only one of the above criteria, whereas others may lack several. How is urban density defined?The density of a geographic area is measured on the basis of the average number of people per unit of area (for example, the number of people per square kilometre, km2). It’s therefore calculated as the population divided by the land area for that given population. But what does urban density mean? Here, again, we encounter the difficulty in agreeing on the standard boundary definition of what constitutes an urban area. The standard metric adopted (and encouraged) by the UN for urban density is the so-called “urban agglomeration population density”. An urban agglomeration is defined by the UN as:
This figure, which shows the urban definition boundaries for Toronto, is used by the UN to demonstrate these differences.23 Here we see that the most commonly used definition of “urban agglomeration” is based on the population and area size of the central city or town plus its close suburban sprawls. How does urbanization affect population distribution?Urbanization can increase population density by restricting animal movement, increasing available forage, or decreasing competition by reducing the population size of competitors (e.g., Crooks and Soule´ 1999, Prange et al.
How did urbanization affect the population of the United States?The US population experienced little growth in urbanization in the first decades of the nineteenth century, with the urbanization rate remaining below 10 percent. From 1830 to 1930, the pace of urbanization substantially accelerated: the share of the population living in an urban area increased six-fold to 60 percent.
What is urbanization and why has it happened in the United States?One important result of industrialization and immigration was the growth of cities, a process known as urbanization. Commonly, factories were located near urban areas. These businesses attracted immigrants and people moving from rural areas who were looking for employment. Cities grew at a rapid rate as a result.
What is the distribution of population in urban areas?By the 1950s, the percentage of the human population living in urban areas was up to around 29%, and by 2009, that number had reached 50%. This number is expected to increase rapidly and by 2050, it is predicted that over 70% of the human population will live in urban areas.
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