["Journal of Regional Science, EarlyView. ", "\nABSTRACT\nMounting evidence suggests the important role of opening‐up policies in stimulating intra‐city economic activities, while this study examines how openness shaped inter‐city connectivity. Drawing on the background of China's treaty ports opened between the 1840s and 1910s, we find that city pairs where both held treaty ports exhibited significantly stronger inter‐city linkages in 1935, as proxied by banking network data. This result holds across various robustness tests and the instrumental variable approach. Finally, we demonstrate that the legacy of treaty ports, transmitted in part through historical inter‐city connectivity, continues to reactivate contemporary urban linkages–as reflected not only in banking networks, but also in population flows, airline frequency, high‐tech investment, knowledge collaboration, and state‐led high‐speed rail linkages, indicating the enduring and far‐reaching effect of the regional opening‐up.\n"]