Population density

Population density (in agriculture: standing stock or plant density) is a measurement of population per unit land area. It is mostly applied to humans, but sometimes to other living organisms. It is a key geographical term.[1] In simple terms, population density refers to the number of people living in an area per square kilometre, or other unit of land area.

Population density (people per km2) by country or U.S. state in 2019
Population density (people per km2) map of the world in 1994. In relation to the equator it is seen that the vast majority of human population lives in the Northern Hemisphere, as 67% of Earth's land area is there.

Biological population densities

Population density is population divided by total land area, sometimes including seas and oceans, as appropriate.[1]

Low densities may cause an extinction vortex and further reduce fertility. This is called the Allee effect after the scientist who identified it. Examples of the causes of reduced fertility in low population densities are [2]

  • Increased problems with locating sexual mates
  • Increased inbreeding

Human densities
Population density (people per km2) by country, 2006
Population density (people per km2) map of the world in 2005

Population density is the number of people per unit of area, usually transcribed as "per square kilometer" or square mile, and which may include or exclude, for example, areas of water or glaciers. Commonly this is calculated for a county, city, country, another territory or the entire world.

The world's population is around 7,800,000,000[3] and Earth's total area (including land and water) is 510,000,000 km2 (197,000,000 sq. mi.).[4] Therefore, from this very crude type of calculation, the worldwide human population density is approximately 7,800,000,000 ÷ 510,000,000 = 15.3/km2 (40 per sq. mi.). However, if only the Earth's land area of 150,000,000 km2 (58,000,000 sq. mi.) is taken into account, then human population density is 50/km2 (129 per sq. mi.). This includes all continental and island land area, including Antarctica. But if Antarctica is excluded, then population density rises to over 55 persons/km2 (over 142 per sq. mi.).[1]

World environments map provided for comparison with maps above

Several of the most densely populated territories in the world are city-states, microstates and urban dependencies.[5][6] In fact, 95% of the world's population is concentrated on just 10% of the world's land.[7] These territories have a relatively small area and a high urbanization level, with an economically specialized city population drawing also on rural resources outside the area, illustrating the difference between high population density and overpopulation.

Deserts have very limited potential for growing crops as there is not enough rain to support them. Thus, their population density is generally low. However, some cities in the Middle East, such as Dubai, have been increasing in population and infrastructure growth at a fast pace.[8]

Mongolian Steppes. Mongolia is the least densely populated country in the world due to its harsh climate as a result of its geography.[9]

Cities with high population densities are, by some, considered to be overpopulated, though this will depend on factors like quality of housing and infrastructure and access to resources.[10] Very densely populated cities are mostly in Asia (particularly Southeast Asia); Africa's Lagos, Kinshasa, and Cairo; South America's Bogotá, Lima, and São Paulo; and Mexico City and Saint Petersburg also fall into this category.[11]

Monaco is currently the most densely populated nation in Europe.

City population and especially area are, however, heavily dependent on the definition of "urban area" used: densities are almost invariably higher for the center only than when suburban settlements and intervening rural areas are included, as in the agglomeration or metropolitan area (the latter sometimes including neighboring cities).

In comparison, based on a world population of 7.8 billion, the world's inhabitants, if conceptualized as a loose crowd occupying just under 1 m2 (10 sq. ft) per person (cf. Jacobs Method), would occupy a space a little larger than Delaware's land area.

Countries and dependent territories
Population under 10,000,000
Rank Country or
dependent territory		 Area Population Density
km2 sq. mi. per km2 per sq.
mi.
1  Macau (China) 30.5 12 650,834 21,339 55,268
2  Monaco 2.02 0.78 37,550 18,589 48,145
3  Singapore 719.9 278 5,612,300 7,796 20,192
4  Hong Kong (China) 1,106.3 427 7,409,800 6,698 17,348
5  Gibraltar (UK)[12] 6.8 2.6 33,140 4,874 12,624
6  Bahrain 757 292 1,451,200 1,917 4,965
7   Vatican City 0.44 0.17 800 1,818 4,709
8  Malta 315 122 475,701 1,510 3,911
9  Maldives 298 115 378,114 1,269 3,287
10  Bermuda (UK) 52 20 63,779 1,227 3,178
Population above 10,000,000
Rank
 Country Area Population Density
km2 sq. mi. per km2 per sq.
mi.
6  Bangladesh 143,998 55,598 170,329,768 1,183 3,064
10  Taiwan 36,193 13,974 23,539,588 650 1,683
13  South Korea 100,210 38,691 51,824,142 517 1,339
14  Rwanda 26,338 10,169 12,955,768 492 1,274
16  Burundi 27,816 10,740 12,574,571 452 1,171
17  Haiti 27,065 10,450 11,743,017 434 1,124
18  Netherlands 41,526 16,033 17,572,831 423 1,096
19  India 3,287,240 1,269,210 1,374,547,140 418 1,083
22  Belgium 30,528 11,787 11,554,449 378 979
23  Philippines 300,000 115,831 109,961,895 367 951

Other methods of measurement
This population cartogram of the European Union (2007–2012) uses areas and colors to represent population.
Living population density by country

Although the arithmetic density is the most common way of measuring population density, several other methods have been developed to provide alternative measures of population density over a specific area.

  • Arithmetic density: The total number of people / area of land
  • Physiological density: The total population / area of arable land
  • Agricultural density: The total rural population / area of arable land
  • Residential density: The number of people living in an urban area / area of residential land
  • Urban density: The number of people inhabiting an urban area / total area of urban land
  • Ecological optimum: The density of population that can be supported by the natural resources
  • Living density: Population density at which the average person lives[13]

See also
  • Distance sampling
  • Demography
  • Human geography
  • Idealised population
  • List of population concern organizations
  • Plant density
  • Population dynamics
  • Population decline
  • Population growth
  • Population genetics
  • Population health
  • Population momentum
  • Population pyramid
  • Rural transport problem
  • Small population size

Lists of entities by population density
  • List of Australian suburbs by population density
  • List of countries by population density
  • List of cities by population density
  • List of city districts by population density
  • List of English districts by population density
  • List of European Union cities proper by population density
  • List of islands by population density
  • List of states and territories of the United States by population density

References
  1. Matt Rosenberg Population Density. Geography.about.com. March 2, 2011. Retrieved on December 10, 2011.
  2. Minimum viable population size. Archived October 6, 2012, at the Wayback Machine Eoearth.org (March 6, 2010). Retrieved on December 10, 2011.
  3. U.S. & World Population Clocks. Census.gov. Retrieved on December 10, 2011.
  4. World. CIA World Factbook
  5. Department of Economic and Social Affairs Population Division (2009). "World Population Prospects, Table A.1" (PDF). 2008 revision. United Nations. Retrieved March 12, 2009. {{cite journal}}: Cite journal requires |journal= (help)
  6. The Monaco government uses a smaller surface area figure resulting in a population density of 18,078 per km2
  7. "Urbanization: 95% Of The World's Population Lives On 10% Of The Land". ScienceDaily. Retrieved September 1, 2020.
  8. Portnov, B. A.; Hare, A. Paul (1999). Desert regions : population, migration, and environment. Springer. ISBN 3540657800. OCLC 41320143.
  9. "Why Mongolia is sparsely populated?". Esther Fleming. SidmartinBio.
  10. Human Population. Global Issues. Retrieved on December 10, 2011.
  11. The largest cities in the world by land area, population and density Archived May 16, 2015, at the Wayback Machine. Citymayors.com. Retrieved on December 10, 2011.
  12. Territory claimed by Spain.
  13. Analysis of living population density per countries, based on NASA SEDAC world gridded data.
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