How fast do big cities grow?

By: Jihad El-Shebeni

According to a UN report on the world's cities in 2016, an estimated 54.5 per cent of the world’s population lived in urban settlements.
In 2016, 1.7 billion people—23 per cent of the world’s population—lived in a city with at least 1 million inhabitants.

A minority of people reside in megacities—500 million, representing 6.8 per cent of the global population in 2016. But, as these cities increase in both size and number, they will become home to a growing share of the population.
Of the world’s 31 megacities (that is, cities with 10 million inhabitants or more) in 2016, 24 are located in the less developed regions or the “global South”. China alone was home to six megacities in 2016, while India had five.

In Northern America, more than half of the population resided in cities with 500,000 inhabitants or more in 2016 and one in five people lived in a city of5 million inhabitants or more. Latin America and the Caribbean is the region with the largest proportion of the population concentrated in megacities: of the total population of the region in 2016, 12.7 per cent resided in the five cities with 10 million inhabitants or more. In both Africa and Asia, more than half of the population lived in rural areas in 2016, but that share is declining. 
Between 2000 and 2016, the world’s cities with 500,000 inhabitants or more grew at an average annual rate of 2.4 per cent. However, 47 of these cities grew more than twice as fast, with average growth in excess of 6 per cent per year. Of these, 6 are located in Africa, 40 in Asia (20 in China alone), 
Band 1 in Northern America. Among the fastest growing cities, 31 (nearly two thirds) have a long history of rapid population growth, with average annual growth rates above 6 per cent for the period 1980-2000 as well. None of the 47 fastest growing cities had a population greater than 5 million in 2000, only 4 had between 1 and 5 million inhabitants, and43 had fewer than 1 million inhabitants.

Population decline in some cities occurred in response to a natural disaster. This has been the case in the United States city of New Orleans, which lost population after Hurricane Katrina in 2005, and in Sendai, Japan, following the 2011 earthquake and tsunami. Economic contraction has also contributed to population decline in places such as Buffalo and Detroit, concurrent with the loss of industry and jobs in those cities.

In most cases, however, city population decline has been associated not with crises, but rather with persistent low fertility rates, which have contributed to stagnating or declining total population sizes in some countries, particularly in Europe. The 55 cities with declining populations were home to 70 million people in 2016.

In 28 countries or areas, more than 40 per cent of the urban population is concentrated in a single city of more than one million inhabitants. These “primate cities” include Hong Kong, Special Administrative Region (SAR) of China, with 7.4 million inhabitants in 2016, and Singapore, a city-state with 5.7 million inhabitants. An additional five cities concentrate more than 60 per cent of the urban population of their respective country or area, including Brazzaville (Congo), Kuwait City (Kuwait), Panama City (Panama), San Juan (Puerto Rico), and Ulaanbaatar (Mongolia). For just over half of primate cities, the share of the urban population concentrated in the city has increased over time. The proportion of Mongolia’s urban residents living in Ulaanbaatar, for example, rose from 56 per cent in 2000 to almost 66 per cent in 2016. 

The share of Georgia’s urban population residing in Tbilisi increased from 44 per cent in 2000 to nearly 50 per cent in 2016. Some primate cities are experiencing a decline in their share of the urban population. Lisbon, for example, held close to 48 per cent of the urban population of Portugal in2000, but 43 per cent in 2016. The proportion of Guinea’s urban dwellers residing in Conakry also declined from 45 per cent in 2000 to 42 per cent in 2016.