When investigating migration flows, researchers have discovered that the predisposition of young people to migrate could be consistently higher than other age groups when the area of origin is rural. This type of migration, from rural settlements to urban locations, is almost always permanent. It is frequently preceded by several rural-to-rural movements as a process of progressive adaptation to more complex social environments. Both stage and stepwise migration characterize the rural flows among several small towns (Muniz 1981). Flows from urban to rural areas also exist; one example of this kind is known as "back-to-the-land movement" (Jacob 1996, 1997; Halfacree 2007), where urbanites decide to leave their congested places to reside in rural areas where they can have better quality of life. Such migration flows are found generally in more developed countries, while rural-to-urban flows are much more typical in less developed countries.
The question of how far migrants can travel has been the focus of the classical migration studies since Ravenstein's Law of Migration, which recognized the relevance of distance as a factor of migration (Ravenstein 1885). One of the basic works on migration and distance investigates population movements from one city to another. George Zipf (1946) tried to explain urban-to-urban migration by the principle of least effort. According to Zipf's theory, the number of migrants from one city to another is a function of the distance separating the cities, since the effort and cost required to cover greater distances would increase with the distance traveled. Traditionally, geographers recognize that the "friction of distance" acts on human movements, meaning that the frequency of these movements decreases with increasing distance. This relationship is known as distance-decay or inverse-distance relationships.
Figure 1 shows how people move (flow I) from a small place (represented by the number 5) to place 4 in greater numbers than from place 4 to place 3 (flow II) and consecutively to place 2 (flow III) and place 1 (flow IV) due to the friction of distance, as represented by the smaller arrows. Larger cities, however, tend to have more influence on a greater number of migrants, so a theory of migration should also account for the size of the receiving places as well as the distance.
Figure 1. Zipf's Inverse Distance Law
Source: Based on Zipf (1946).
Pause and Reflect 1:
To what degree is the distance-decay concept evident in the data on migration histories your class gathered in the previous activity?
Were examples of stage or stepwise migration evident?