Comparing the physical, functional and knowledge integration of the Yangtze River Delta city-region through the lens of inter-city networks

•Analysis of the regional integration in the Yangtze River Delta based on interactions between its key cities•The intensity of the inter-city interactions is benchmarked against a gravity model•Regional integration is tested for physical, functional and knowledge dimensions•A distinct administrative-hierarchical bias can be identified in all three networks•This indicates that the Yangtze River Delta region is not (yet) a fully integrated region