Farther apart, faltering partnerships? The impact of geographical separation on research collaboration

While technological advancements have reduced barriers to remote collaboration, the extent to which geographical proximity still shapes research outcomes remains a critical yet underexplored question. This study examines how geographical separation, defined as the loss of city-level co-location following collaborator mobility, affects the performance of established research collaborations. Using a quasi-experimental design, we analyze changes in research outcomes among 16,505 scientist pairs following inter-city relocation (treatment group) relative to intra-city relocation (control group). Our findings reveal that geographical separation leads to significant declines in both collaborative productivity (co-authored publications) and scientific impact (citation counts), underscoring the persistent role of proximity in sustaining effective collaboration. We further document important heterogeneity: interdisciplinary collaborations are more resilient in maintaining publication output but experience larger declines in scientific impact; same-stage collaborations are more vulnerable than cross-stage collaborations; and the negative effect is stronger in geographically larger countries. These findings highlight the enduring importance of geographical proximity in maintaining effective research collaboration.