title: A model of urbanization with nonlinear migration flows.
abstract: "This paper seeks an appropriate specification of the migration exchange between rural and urban areas so that the implied evolution of the degree of urbanization agrees with its commonly observed S-shape.  After demonstrating that the gross migration flows between rural and urban areas should be specified as nonlinear functions of the population in the origin sector, the paper introduces a model in which such flows are represented by gravity-type functional forms....[The model] can be used to give insights into the time paths of three basic urbanization variables:  the urban-rural growth rate differential, the rural net outmigration rate, and the urban net immigration rate.  All take on a zero value at the two extremes of the urbanization process and evolve in between according to a bell-shaped curve. These findings are illustrated by applying the model to data from the United States for the period 1790-1980."
authors.forename: J
authors.initials: J
authors.lastname: Ledent
mesh_terms: D000569:Americas; D003710:Demography; D019049:Developed Countries; D003906:Developing Countries; D004641:Emigration and Immigration; D005843:Geography; D008962:Models, Theoretical; D009656:North America; D011153:Population; D011157:Population Dynamics; D012106:Research; D014481:United States; D014505:Urban Population; D014507:Urbanization
keywords: Americas; Demographic Factors; Developed Countries; Developing Countries; Geographic Factors; Historical Survey; Migration; Models, Theoretical; North America; Northern America; Population; Population Dynamics; Research Methodology; Rural-urban Migration; Spatial Distribution; United States; Urban Spatial Distribution; Urbanization