Growth due to immigration has reached a strong intensity, as a result of the large-scale rural exodus “which literally empties the countryside, especially in Latin America and Africa, of its younger and more enterprising elements” (14). refers to the Ibero-American countries as a whole, some rough calculations estimate that between 1940 and 1970 the rural exodus meant the deficit of some 51 million people who in the same figures would have gone to the cities, representing 63 percent of the total increase in the urban sector in those three decades (15). The proportion of foreign-born in many cities has thus risen to considerable figures: in the 1960s it could be 33% of immigrants in Santiago de Chile, 58% in Buenos Aires and 74% in several Brazilian cities, among which Sâo Paulo, Rio de Janeiro and Belo Horizonte (16).
Migration is a process of spatial and social mobility that has allowed the occupation of all terrestrial space and the improvement of the living conditions of humanity. As we have seen, it has allowed cities to maintain their population and develop their economic activity.
In traditional societies, even in the most static ones, spatial mobility becomes, in general, necessary with the increase of the family. The dominant family structures in many societies, for example, in the European one, imply that a part of the children must leave the paternal house to settle separately. This can be done close to the family home or, very often, at a greater distance, which also includes spatial mobility to places where there are possibilities of subsistence.
In some societies, such as pre-industrial Europe, emigration to cities is part of a more general process of social stratification and occupational redistribution.
It was not simply rural vegetative growth or the necessities of survival in the agrarian sector that led to emigration to the cities. The same agriculture and rural crafts could absorb a part of the population growth. In the 17th and 18th centuries, proto-industrialization in rural areas also became a possibility offered to potential migrants.
But cities were also very attractive because they offered greater opportunities for survival and work. And they also allowed to increase the nuptial possibilities, improve education, and provide greater physical security, and legal or religious freedom.