1. Most migrants move only a short distance, and then typically to major cities. 2. Rapidly growing cities are populated by migrants from nearby rural areas; in turn, the “gaps” left in the rural population are filled by migrants from more distant areas. 3. The process of dispersion is the inverse of the process of absorption and exhibits similar features. 4. Each main current of migration produces a compensating counter current. E.G. Ravensteins's (1885) “Laws of Migration”
5. Long-distance migrants tend to move to major cities. 6. Rural people have a higher propensity to migrate than urban people. 7. Women have a higher propensity to migrate than men. Continued…
Ravenstein leaves little doubt that he believed employment and wage opportunities were the major “determinants” of migration: “In most instances it will be found that they did so (leave their homes) in search of work of a more remunerative or attractive kind than that afforded by the places of their birth.” (1885, p. 181) (parentheses are mine). Later he wrote that “…the call for labour in our centres of industry and commerce is the prime cause of these currents of migration.” (p. 198) Ravenstein does, however, recognize that the motives for migration are “various.”
C. Warren Thornthwaite, Internal Migration in the United States (1934) Carter Goodrich, et al., Migration and Economic Opportunity (1936) Dorothy Swaine Thomas, Research Memorandum on Migration Differentials (1938) Thomas: Confirms Ravenstein's earlier work regarding U.S. Goodrich, et al.: Migration is response to changing job opportunities. Also provides a detailed description of U.S. internal migration going back to the 1850 census which was the first U.S. census to provide lifetime migration data.
H. Makower, J. Marschak, and H.W. Robinson (series of, in Oxford Economic Papers during the late 1930s). They focus on two “incentives” to migrate a. relative unemployment discrepancy (Ui – Un) / Un b. distance Also considered the lag between incentive to move and migration.
They anticipated the “gravity model” of migration “Quite a close relationship was found between discrepancies in the unemployment rates and migration of labour where allowance was made for the size of the insured population and the distance over which migrants had to travel.” “An increase of distance by 1 percent reduces migration by from 1.6 percent to 2.1 percent.”
The Gravity Model J.Q. Stewart (1941) F = GPiPj / D²ĳ Where F = gravitational or demographic force G = constant Pi = population of origin Pj = population of destination Dij = distance from i to j
Mij= GPiPjDijα Mij= GPiβ1Pjβ2 Dijα
“Modified” Gravity Models lnMij= lnβo +β1lnPi+β2lnPj+ β3lnDij + β4lnYi+β5lnYj m + ∑ βinXin n=1 m + ∑ βjnXjn n=1