Some factors affecting marital distances have been studied in two Outer Hebridean islands, Harris (843 marriages) and Barra (444 marriages), over the period 1855-1990. In each island marital distances fell before 1900, but then rose to their greatest values after the 1950s. Fishermen generally married at the shortest distances and men in land-based occupations at the longest. The depression in the fishing industry during the 1880s and early 1890s was associated with reductions in marital distances, especially among fishermen. In the different regions of Harris, marital distances were least in the south-east, where settlement was most dense, and greatest in the south-west where it was most sparse.

When the association between marital frequencies and inter-settlement distances was studied, it was found that for Harris there was, overall, a trend to endogamous and short-distance marriage. However, this trend was only slight during 1955-90. For Barra a similar trend was found before 1955, but thereafter there appeared to be virtually no connection between marital frequency and inter-settlement distance. Thus the only constraint on marriage was the spatial distribution of settlements. In this situation the chances of random mating with respect to distance are maximised.

Application of ‘Central Place’ theory suggested that only since 1946 can any tendency be detected to regard Tarbert in Harris or Castlebay in Barra as Central Places, at least as far as marriage is concerned. In each island the tendency appears to be limited to the settlements closest to the Central Place.