Residential mobility--the change of residence within a country--is a pervasive phenomenon in 21st century societies, with the peak clearly being in young adulthood. Placing the self in geographical space has now become a major challenge for young adults, making region a key identity domain. Little is known, however, about the correlates of regional identity development. In line with the dynamic-transactional paradigm, we expected longitudinal associations between regional identity and the geographical dispersion of personal relationships. We specifically assumed that both individual experiences--such as moving--and personal relationship experiences--such as emotional closeness toward relationship partners--moderate these associations over time. Using longitudinal multilevel analyses, we found support for these hypotheses in a 3-wave longitudinal study over 1 year with 1,059 postsecondary graduates from Germany (73% female, mean age 24.53 years). Most notably, changes in regional identity were related to changes in geographical distance from personal relationship partners. Effects were robust and confirmed when controlling for diverse reasons for moving. We conclude that regional identity and personal relationships share a common developmental pathway. This pathway also points toward the relevance of geographical distance from personal relationships, even in young adults' mobile and connected world.