Hierarchical Internal Migration Regions of France

Internal migration tables can be employed to ascertain functional migration regions¿collections of geographic units with relatively large intraregional flows and relatively small interregional movements. A two-stage algorithm that has been utilized to study tables for various nations is applied here to a 21 × 21 French matrix. In the first step, the square table is adjusted to possess uniform marginal (row and column) sums. The doubly standardized table obtained can be regarded as an asymmetric similarity matrix. It serves, in the second stage, as input to a hierarchical clustering procedure, based on the concep of the strong components of a directed graph. Région Parisienne and Centre are shown to have the broadest migration bases. Well-defined southern and northwestern regions are found.