The answer to this question is not an easy one, as most urbanist immediately would agree that economic and social issues are involved and yet it confirms again, why urbanisation is about everything. However, the answer is probably in the Urbanisation Cycle Theory. Cities throughout the world in developing countries and developed countries seem to confirm the urbanisation cycle that explains how cities have been developed in the, let us say, last 150 years. The urbanisation cycle is as well explained as the theory of differential urbanisation by Pacione (2009) and Geyer & Kontuly in 1993, which in short explains the 4 transition phases of cities. It could be referred as well as the Urbanisation Transition in which cities grow, suburbanise and expand, and after all reurbanise:

FIRST! Urbanisation!

There is the primate city phase: In this phase, cities grow tremendously because of a strong massive in-migration from smaller cities and rural areas. This was especially observable in Europe and the United States in the 19th century because of an agricultural decline towards an industrial economy. Many people moved into cities to work in production industries. Cities were growing so fast that there was not enough space for all of the migrants. As a result, many people lived in slums under unhygienic conditions in the 19th century. The hard conditions of cities in the Western world resemble many examples in urbanising cities in Africa. On the African continent and South East Asia, new service economies are developing in combination of a deteriorating agriculture leading to a high in-migration towards big cities. In countries with a poor fiscal capacity, corruption, and informal housing are leading to major slums under bad liveable conditions. Such as in Jakarta, Indonesia on the picture, are there many more examples throughout the developing world. More economic growth and transport change such as the broad use of the car can lead to the next urban phase!

SECOND! Suburbanisation!

In this phase, the primate city is bursting due to the strong in-migration resulting to urban problems such as congestion and economic inefficiencies. Residents and companies start to relocate outside of the central business district (CBD) towards more suburban locations. New neighbourhoods and small cities start to grow that were surrounding the primate city. More economic growth and a growing middle-class means that more people can afford a car and more people can afford to leave the city centre and to escape the congested unhygienic conditions in the city centre. Whereas this has happened in the UK and USA in the beginning of the 20th century, present examples are apparent in Turkey like the city Bentderesi on the picture, Russia, and India, which show a strong economic growth. Examples of suburbanisation are as well visible in African cities such as Accra in Ghana, Lagos in Nigeria and Luanda in Angola.

THIRD! Counterurbanisation!

After suburbanisation, the rise of living costs in the city centre forces more people to leave the CBD and the suburbs leading to migration movements outside the metropolitan city area towards smaller cities and villages surrounding the metropolitan area. The attraction towards tranquillity, a greener environment is often considered as child-friendly. In combination of low house prices and more space, people were leaving urban areas. In the USA, further counterurbanisation has become visible in most metropolitan areas escaping the high living costs in the cities and enjoying green areas. This phase was first present in the USA and UK from the 1960s and later on in Western Europe. Counterurbanisation occurs mainly under a good transport network, decentralised employment and with a service economy rather a production economy. The main force of counterurbanisation in developing countries was based on decentralising families longing to a more child-friendly, greener environment to escape the congestion and city pollution. Which need after all a good infrastructure when the head of the family commutes to his work. Countries such as India stick at the suburbanisation phase due to a lack of efficient infrastructure, public transport network, and insufficient fiscal capacity to build and maintain a good infrastructure.

FOURTH! Reurbanisation!

The fourth and last trend is reurbanisation, which is the last observable trend in Western Europe and the USA. Cities and their unique public areas offer a high facility rate of cultural, leisure, economic and public offer and keep the city an attractive place for different kind of people. A strong movement to live in the city has become apparent throughout the Western world for people that would like to enjoy the unique city life. New apartments and a reuse of old buildings is now the present trend in developed cities. Policy makers see the advantages of new resident locations in the city centre along with new creative companies that demand a fancy urban location. After all, cities were and still are the main location for cultural, public events and economic activities. Stock exchange, businesses, retail, politics, museums, and concerts do prefer the city and more people seem to appreciate city life.

Important sources:

-Geyer HS & Kontuly T 1993. A theoretical foundation for the concept of differential urbanization. International Regional Science Review 12: 157-177.