The Cerdanya valley in the eastern Pyrenees has a physical unity into which a political frontier has been imposed to divide it. The social and cultural repercussions of this Franco-Spanish border have created obstacles to marriage which are not due to topography. Choice of month of marriage is under cultural control and the study of seasonality in marriages recorded in the registers of all the Cerdan parishes on both sides of the border demonstrated differences over time and between French and Spanish sectors. It is suggested that these changes demonstrate the process of distancing of the two populations. Cluster and correspondence analysis showed progressive differentiation of the seasonality patterns of the French and Spanish Cerdans despite the geographic unity of the valley. Sociocultural factors are presumed responsible.

In this paper the records of 7844 marriages in the parishes of French and Spanish sectors of the Cerdanya Valley have been analysed. The Cerdanya is an eastern Pyrenean valley, today divided by the Franco-Spanish border, but once united within Catalonia. The results have been reported on the one hand on a small scale using local place names, and on the other hand on a wider scale across France and Spain, because interest lies both in the geographic range from which some marital partners have come and in the relative proportions of brides and grooms from the French and Spanish parts of Cerdanya and from adjacent districts. Both mountains and the Franco-Spanish border are shown to have reduced the likelihood of marriage. Inaccessible mountain barriers appear to have been a greater obstacle to marital movement than the border. Adjacent districts and local provinces have provided a greater proportion of brides and grooms than more distant ones, but thereafter frequencies from the further regions do not decrease with greater distance. More marital partners have moved from Spain to France than vice-versa, and mobility of grooms exceeded mobility of brides. Results are relevant to genetics and the current European interest in nationality and ethnicity.