摘要：Extensive as the Iiterature on migration has become, substantial gaps have remained in our knowledge of the spatial dimensions of the process. In the analysis of flow patterns, primary attention has been given to the broader interregional movement of population between provinces or other major areal units. Data constraints have impeded the measurement of migration transfers between the rural and urban sectors or any comprehensive investigation of the population exchanges of towns and cities in the middle and lower orders of the urban hierarchy, including the impact of the migration process on the growth dynamics and demographic structure of these centres. A general trend towards demetropolitanization in North America in the 1960s and 1970s received widespread attention in the literature, but the types of data available were not adequate to trace, in any precise fashion, the spatial pattern of dispersion or to pinpoint the levels of the ruralurban system that were gaining from this outflow. In Canada, many of these gaps in our knowledge can now be filled. Improvements in the data base have opened the way for the analysis of the migration process at a scale that is still beyond the reach of researchers in most other countries.
