Calculation and influencing factors of the sustainable development of urban industries: a case study of China's state-level new districts

China's state-level new districts (SNDs) have become the new growth poles for the economic development of the cities where they are located, and a reasonable industrial structure is crucial to industrial sustainable development of SNDs and urban economic growth. This study uses multi-dimensional indicators to measure the convergence level of industrial structure among SNDs and reveals its dynamic evolution trend and formation mechanism. In this context, this study uses dynamic panel model to test the effect of various factors on the convergence of industrial structure. The results are as follows: the advantageous industries in Pudong New District (PND) and Liangjiang New District (LND) are concentrated in capital-intensive and technology-intensive industries. The advantageous industries in Binhai New District (BND) are scattered, and its advantageous industries are distributed in resource-intensive, technology-intensive, and capital-intensive industries. There is an obvious convergence of industrial structure among SNDs, but the degree of convergence of industrial structure among SNDs is different. The result of the regression model shows that the convergence of industrial structure has a significant cumulative effect; investment scale (IS) and government intervention (GI) significantly increase the convergence level of industrial structure, while market demand (MD) and technology level (TL) significantly decrease it. Moreover, the effects of GI and MD on industrial structure convergence are stronger.