Migration is the relatively permanent movement of individuals or groups over varying distances to change places of residence; permanence and distance are its major defining dimensions. Internal migration occurs within the boundaries of a given country. (International migrants, not considered here, are called immigrants.) Internal migration, therefore, is a type of geographic mobility status.

Definitions

The following definitions are standard in the field of social demography (Bogue 1985):

Mobility status. A classification of the population based on a comparison between the place of residence (destination) of each individual in a census enumeration or survey and the place of residence (origin) at some specified earlier date. Mobility status in terms of the distance of the move falls into four main categories: nonmovers, local movers, intrastate migrants, and interstate migrants. They may be examined more specifically in the list below:

1. Nonmovers, or nonmobile persons, live in the same house...