Bridge accessibility and population agglomeration: Evidence from Yangtze River Bridges in China

Transportation infrastructure plays a pivotal role in shaping regional population distribution. While existing studies have examined the impacts of high-speed railways, highways, and subway systems, the role of bridges as a distinctive form of transport infrastructure has received limited scholarly focus. Using panel data of 1 km × 1 km spatial grids in the 20 km buffer zone along the Yangtze River from 2001 to 2023, this study examines the impact of bridge accessibility on population growth. The results reveal that improved bridge accessibility significantly promotes population agglomeration. Specifically, a 1% reduction in the distance to the nearest bridge is associated with a 1.16% increase in population density. Mechanism analysis provides suggestive evidence that reductions in business costs, accelerated urbanization, and the clustering of amenities are plausible channels through which improved bridge accessibility promotes population growth. Heterogeneity analysis further demonstrates that the effects are particularly pronounced in grids influenced by multiple bridges, located within 10 km of the river, situated within a 0–60° bridge radiation angle, lying in inter-provincial border areas, or positioned across the river from municipal governments. By providing micro-spatial evidence on the demographic effects of bridge accessibility, this study contributes to the literature on transport infrastructure and population distribution and offers policy-relevant insights for regions with similar geographic conditions.