Urbanisation and international migration

Urbanisation is the growth of cities and of the urban share of population and the spread of an urban way of life. Large cities existed in antiquity, but real urbanisation came with the industrial revolution in the 19th century in Europe, then North America, and from the middle of the 20th century in developing countries. The urban share of world population was only a few percent in 1800, passed 50% in the late 2000s (around 2007) and is now roughly 57%. Urbanisation is divided into three stages: forming (urban share below 50%, new cities appear), developed (share rises above 50%, million-cities and agglomerations grow) and mature (people move to the outskirts – suburbanisation; the difference between city and countryside fades – rurbanisation). When the influence of the largest cities spreads beyond their own country to the world they are called global cities (New York, London, Tokyo and others). Problems include pollution, water supply, traffic congestion, housing costs and social inequality.