GENERAL THEORIES OF GEOGRAPHIC MOBILITY
A general survey
of geographic mobility literature reveals numerous sociological and demographic
studies, as well as ample data. Existing
models can be included within the following five categories:
I. Typologies; Petersen's Typology of Migration (Petersen, 1958). According to Petersen,
“Migration is not
unitary; it differs from fertility and mortality in that it cannot be analyzed,
even primarily in terms of supra cultural, physiological factors but must be differentiated
even at the most abstract level with the social conditions obtaining. This means that the most general statement that one can make
concerning migration must be in the form of a typology, rather than a
law” (Petersen, 1969, p. 229).
Petersen’s typology
divided migration into five classes: primitive,
impelled, forced, free, and mass. Each class was subdivided into two
types; conservative migration, in which the mover changes residence to maintain
his present standard of living, and innovative migration where the move is made
in order to improve the living standards. Although there is evidence to support
the existence of each class of migration in the
II. Models based upon "general principles" or "Laws" formulated to explain geographic mobility; Ravenstein1s Laws of Migration, (Ravenstein, 1889). The "Laws of Migration" proposed by Ravenstein in 1889 were intended to explain the movement of people without regard to any particular temporal situation or location (Bogue, 1969). Ravenstein's exhaustive study appeared in the Journal of the Royal Statistical Society, Vol. 52, No. 2, Jun., 1889, (pages 241-305). Writing at a time of intense internal and international migration, Ravenstein states in his general conclusion:
“Having thus placed
before you a vast array of facts and figures, I venture to deduce from them
certain principles or laws which appear to me to guide all migratory movements.
I do not question for a moment that the principal, though not the only cause of
migration has to be sought for in overpopulation in one part of the country,
whilst there exist elsewhere undeveloped resources which hold out greater
promise for remunerative labor. It is obvious that this is not the only cause.
Bad or oppressive laws, heavy taxation, an unattractive climate, uncongenial
social surroundings, and even compulsion (slave trade, transportation), all
have produced and are still producing currents of migration, but none of these
currents can compare in volume with that which arises from the desire inherent
in most men to "better" themselves in material respects. It is in
thus that the surplus population of one part of the country drifts into another
part, where the development of industry and commerce, or the possibility of
procuring productive land still in a state of nature, call for more hands to
labor. But how is this call supplied? Suppose there exists
a surplus of labor in one province and a deficiency in another, whilst the
intervening provinces are able to find remunerative occupation for all their
inhabitants. Will the laborer, in search of work, travel across these
intervening provinces in order to supply the deficiency? I say, no!”
Thus, having emphasized an economic motive for migration--"the desire inherent in most men to ‘better themselves in material respects’" Ravenstein concludes;
1.) "…under normal conditions the migratory movement will be a gradual one; it will proceed step by step, and will well be transmitted form province to province." (p. 286)
2.) "…the bulk of the migrants ought to travel short distances only, and that they really do this even in America, where the conditions are quite exceptional, I believe I have amply proved." (p. 286)
3. "…each main current produces a counter current of feebler strength." (p. 287)
4. [Most moves are from surrounding rural areas into the towns and cities]. (p. 28)
5. "Females appear to predominate among short-journey migrants...” (p. 288)
6. "Wherever I was able to make a
comparison I found that an increase in the means of
locomotion and a development of manufactures and commerce have led to an
increase of migration. Migration means life and progress; a sedentary
population stagnation." (p. 288)
III. Gravitational Models; Stouffer's Theory of Intervening Opportunities (Stouffer, 1940); Zipf's PIP2/D Hypothesis (Zipf, 1946).
IV. Models which stress individual or family
decision processes influencing geographic mobility; Rossi's Theory (Rossi,
1955);
V. Push-Pull Models;
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Everett Lee’s Push-Pull Theory
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