Fewer Crashes but a Smaller Decline in Fatality Risk: Rethinking Road Safety Indicators for Shrinking Regions in Korea

Population decline can undermine access to essential services and safe mobility. Korea designated 89 municipalities as depopulating areas in 2021 and launched the Local Extinction Response Fund in 2022. We examined whether road safety outcomes improved more in designated than in non-designated municipalities using a balanced 2015–2025 panel based on crash and population data, supplemented by cause-of-death statistics for age standardization and cross-validation. Poisson pseudo-maximum-likelihood difference-in-differences models compared 2015–2020 with 2022–2025. Population-based crash frequency declined 9.0% more in designated areas (incidence rate ratio (IRR) = 0.910, 95% confidence interval (CI) 0.863–0.960), whereas age-standardized fatality risk declined less (IRR = 1.086, 95% CI 1.020–1.156). Because the relative crash decline began in 2021, before Fund implementation, and because the fatality estimate was sensitive to alternative exposure definitions and to allowing a differential pre-existing trend, these findings are interpreted as comparative pre-to-post changes rather than as causal effects of the Fund. The fatality gap was larger in municipalities where depopulation designation overlapped with emergency-care underserved status, but similar differences appeared for crashes and serious injuries, while deaths per 100 crashes showed no clear interaction. Road safety evaluation in depopulating areas should consider crash frequency, serious injuries, and fatalities together, alongside broader regional vulnerabilities. These findings can support future multidimensional road safety monitoring and help prioritize safety and emergency-care interventions in shrinking regions.