STRUCTURAL DETERMINANTS 0 F MIGRATION A large number of factors associated with the development process influence patterns of migra- tion in the Third World. They may be divided into rural push factors and urban pull factors. RURAL PUSH FACTORS 1. Population-growth rates. One of the most com- mon explanations for out-migration is the high rate of population growth in rural areas. This informed economic models of migration in the 1950s and 1960s in which migration was seen as a movement of surplus labour. However population growth alone is not the main cause of emigration. The effects of demographic