This article draws inspiration from social network analysis (SNA) to investigate the impact of spatial proximity on the geography of strong social ties in three European border regions. We consider cross-border friendship and kinship as a measure of shortdistance transnationalism, examine the conditions under which the latter is likely to emerge, and systematically compares our findings with "traditional" forms of transnationalism. The study is based on a large-scale and representative quantitative survey (N = 3,215) conducted in the Geneva, Lille, and Basque border regions in order to assess the impact of cross-border integration intensity on the inter-personal relationships of all residents, regardless of their migration experiences. The results indicate that only 11.9% of the residents reported having at least one strong cross-border tie. Binomial regression models are used to demonstrate that cross-border ties are not solely shaped by proximity, but also depend on individuals' socioeconomics, on their mobility experiences, and on contextual factors. This article shows that cross-border integration primarily fosters cross-border friendships rather than kinships, and that cross-border ties are not evenly distributed among the population. Individuals born in the studied border regions do not have the highest levels of short-distance transnationalism, raising a discussion about the importance of promoting cross-border rootedness.