How big is too big for a city?

Urban Population

Up to the Industrial Revolution people all over the world lived mainly in the countryside. In 1800, only 3 % of the world’s population lived in cities. In 1900 only 12 cities had more than 1 million people.

Today, about half of the world’s population lives in urban areas. There are over 400 cities with more than a million people. In developed countries, up to 70 % or more live in larger cities, whereas in poorer countries this rate is below 40 %.

During the 19th and the beginning of the 20th century cities grew fast, especially in Europe and North America, because new industries were created there and people found many jobs . Later on cities grew more slowly because they became overcrowded and diseases could spread faster. Today death rates in cites are low because they have better doctors and more hospitals.

In industrialized countries the growth of cities has stopped. New York and London grew very quickly during the 1800s and early 1900s, but since then their growth has slowed down.

African and Asian cities like Lagos, Bombay or Calcutta are growing rapidly and this will probably continue during the next years. About 40 cities around the world have a population of over 5 million . They are called megacities . 80% of them are in poorer countries.

People go to the cities for many reasons. The table shows you what pulls them to the cities and what pushes them away from the countryside.

Pull factors

  • more and better jobs
  • better hospitals and health care
  • better living standards
  • cities are social and financial centres
  • better education—schools and universities

Push factors

  • too many people in the countryside
  • low income
  • not enough raw materials (water, wood etc..)
  • the quality of farming land is getting worse

Can a city become too big?

The number of megacities has been increasing so rapidly in the last few decades that many are experiencing serious growing pains.

There are now some three dozen megacities in the world, each sprawling areas home to more than 10 million people. Bigger cities come with obvious advantages, the increase in people, interactions and infrastructures create more opportunities and efficiencies. But massive population growth has also led to more pollution, spiralling rent, and crumbling infrastructure.

These problems, according to theoretical physicist Geoffrey West, increase alongside population growth. “The bigger you are the more you get per capita. So the bigger you are, the more Aids cases there are, the more higher wages, the more crime there is, the more patents are produced and so forth. All in a systematic, predictable way.”

West says all the super-sized cities around the world seem to share this concept of super-linear scaling. “In order to sustain growth,” he says, “you need to continuously innovate and you need to do it at a faster and faster rate. So that the time between major innovations gets shorter and shorter, and the pace of life has to necessarily get faster and faster to sustain that growth.”

While they may share the same principles, the reasons driving them are very different. Each are under different pressures as they struggle to support increasing numbers. Here are five cautionary tales from megacities, that together paint a fuller picture of the consequences of the spiralling urban population.

  • CAIRO – CONGESTION
  • LONDON – HOUSE PRICES
  • MUMBAI – TRANSPORT
  • JAKARTA – SEA LEVEL
  • SHANGHAI – AIR POLLUTION

By 2030, the United Nations predicts that there will be 41 megacities total with a population of 10 million or more.

Despite the ominous numbers, Geoffrey West has some good news. “If we make it through this critical next 30 years,” says West, “one of the things that will happen, we believe, although it’s very controversial, is that the population overall will stabilize.

“Somewhere towards the three-quarter point of the century we will see an effective slowing really, kind of stabilization of the global population,” he says. “At some stage, associated with that, we might see a stabilization of the migration to cities.” Time will tell if he is correct.

Shanghai to cap population at 25 million to battle ‘big city disease’

SHANGHAI — China’s financial hub of Shanghai will limit its population to 25 million people by 2035 as part of a quest to manage “big city disease”, the cabinet has said.

The State Council said on its website late on Monday the goal to control the size of the city was part of Shanghai’s masterplan for 2017-2035, which the government body had approved.

“By 2035, the resident population in Shanghai will be controlled at around 25 million and the total amount of land made available for construction will not exceed 3,200 square kilometers,” it said.

State media has defined “big city disease” as arising when a megacity becomes plagued with environmental pollution, traffic congestion and a shortage of public services, including education and medical care.

Shanghai shows off its beauty as China's financial hub

A Chinese police officer directs traffic on a busy road in Shanghai, China, on Sept. 27, 2016. Yu shenli / Imaginechina via AP

Many of China’s biggest cities also face surging house prices, stirring fears of a property bubble.

Shanghai, which sits on China’s eastern coast, had a permanent population of 24.15 million at the end of 2015, the official Xinhua news agency said last year.

The city has also said it would intensify efforts to protect the environment and historic site as part of its master plan.

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