Monaco is the most densely populated country in the world, according to the United Nations Department of Economic and Social Affairs Population Division.
The principality, located on France's Mediterranean coast, measures just 2.02 square kilometres. But despite its tiny size, around 26,000 people are squeezed in per square kilometre. This figure is predicted to rise to more than 27,000 by 2025.
Macao, meanwhile, which is designated as a special administrative region in China, is in second place, with a population density of around 20,800 per square kilometre.
The former Portuguese colony, which was handed back to China in 1999, has an area of 23.8 square kilometres, and around 612,00 residents.
By contrast, China, which has a total population of more than 1.3 billion, has around 150 people per square kilometre, UN data shows.
Singapore is the third most densely populated country, averaging around 8155 people per square kilometre. Its landmass, however, far exceeds that of Monaco or Macao, measuring roughly 660 square kilometres. It is also home to more than 5.6 million people.
Of the world’s 10 largest economies, India, which has a population of around 1.32 billion, is the most densely populated, with about 450 people per square kilometre. According to the UN, India’s population will exceed China’s by 2024, when density per square kilometre is expected to have risen to 484.
India is also home to a number of the world’s most densely populated cities, including Mumbai, which has 31,700 people per square kilometre, and Kota, which has 12,100.
Pros and cons of crowding
Having more or less people per square kilometre presents both issues and opportunities.
For example, densely populated areas present problems for governments and policymakers, as they look to provide adequate infrastructure, including sanitation, transportation and housing, for their rapidly expanding populations.
And while in the future densely populated cities may offer improved healthcare, today’s urban environments can concentrate health risks and introduce new hazards, the World Health Organization (WHO) warns.
“Health challenges particularly evident in cities relate to water, environment, violence and injury, noncommunicable diseases, unhealthy diets and physical inactivity, harmful use of alcohol, as well as the risks associated with disease outbreaks, among others,” WHO says.
On the other hand, higher density city environments can be more efficient, with greater public transport use and shorter journeys. Modern high-rise buildings also provide breathing space for more affluent urban dwellers.
While the world’s most crowded cities present major health challenges, a number of studies suggest that living in a densely populated urban area can make you healthier and happier.
For example, a recent study of 419,562 adults by the University of Oxford and the University of Hong Kong found that people living in built-up, residential areas in 22 British cities had lower body-mass indexes and took more exercise than residents of more widely-spaced homes in suburban areas.
Commenting on other research that supports their findings, the authors say: “There is now an increasing body of evidence that several measures of high urban density, including residential density, retail and service density, street-intersection density and land-use diversity, are all associated with lower body-mass index and obesity.”