Rural-urban migration is the moving of people from rural areas into cities. When cities grow rapidly, as in Chicago in the late 19th century or Shanghai a century later, the movement of people from rural communities into cities is considered to be the main cause. This kind of growth is especially commonplace in developing countries. Rural migrants are attracted by the possibilities that cities can offer, but often settle in shanty towns and experience extreme poverty. In the 1980s, this was attempted to be tackled with the urban bias theory which was promoted by Michael Litpon who wrote: "...the most important class conflict in the poor countries of the world today is not between labour and capital. Nor is it between foreign and national interests. It is between rural classes and urban classes. The rural sector contains most of the poverty and most of the low-cost sources of potential advance; but the urban sector contains most of the articulateness, organization and power. So the urban classes have been able to win most of the rounds of the struggle with the countryside..." (Varshney, 1993, p.5) In cities of the developed world in-migration is another important factor causing city growth. In-migration refers to migration from former colonies and similar places. The fact that many immigrants settle in impoverished city centres led to the notion of the "peripheralization of the core", which simply describes that people who used to be at the periphery of the former empires now live right in the centre. Recent developments, such as inner-city redevelopment schemes, mean that new arrivals in cities no longer necessarily settle in the centre. It has been argued that this was never the norm, because settlement pattern differ a great deal between cities. In some developed regions, the reverse effect has occurred, with cities losing population to rural areas, and is particularly common for richer families. This has been possible because of improved communications, and has been caused by factors such as the fear of crime and poor urban environments. Originally termed "white flight", the effect is not restricted to cities with a high ethnic minority population. Other factors are increased attraction to investment in real estate, or the simple desire for a new living experience which is common in countries such as the US and Australia.
