Dialect borders—political regions are better predictors than economy or religion

The impact of geography on language and dialect variation has been subject to a vast number of studies in linguistics, as well as the broader humanities. Most quantitative research concerning dialectology has focused on the relationship between spatial distance and change of dialects. Hypotheses regarding the impact of other geographic, cultural, and social factors have been put forth for many years but have rarely been examined with quantitative methods. In this article, we compare dialect variation in Swiss German morphosyntax with three types of social and cultural variation, namely variation in religion, administration, and economy. These different types of variation have contrasting temporal origins. Religion is, for instance, represented by the borders between Christian denominations, which are a result of the Reformation in the 16th century. In order to compare different types of spatial information in one statistical model, we introduce an approach that is robust for spatial dependencies. On one hand, our results are largely in agreement with previous studies. Spatial distance, for instance, proves to be the most important predictor of dialect variance, with distance measures that more realistically represent the potential for social contact, explaining a higher proportion of variance. On the other hand, most interestingly, we find evidence that administrative borders (i.e. political regions) more profoundly impact Swiss dialects than religion or economy. This opens the floor for the hypothesis that possibly both Swiss dialects and political regions have common origins in ancient migration movements and medieval borders between Alemannic territories.