Urban Conditions and Innovation Performance in Cities Hosting East–West Interregional Co-built Industrial Parks: Evidence from Western China

<title>Abstract</title> <p>East–west interregional co-built industrial parks have increasingly served as important institutional vehicles for organizing cross-regional resource flows and strengthening innovation capacity in China’s less-developed regions. Yet innovation performance continues to vary markedly across western Chinese cities hosting these parks despite the establishment of institutionalized interregional collaboration, and the conditions associated with this variation remain insufficiently understood. Using 102 prefecture-level units in western China that host east–west interregional co-built industrial parks, we apply XGBoost, SHAP and partial dependence plots (PDPs) to identify the factors most strongly associated with variation in comprehensive urban innovation performance and to characterize their nonlinear response patterns. The results show that explanatory importance is concentrated in a small set of conditions. R&amp;D personnel, road freight volume, the number of development zones, GDP density and the number of manufacturing firms make the largest contributions to model predictions. Internal urban conditions contribute more to model predictions than interregional collaboration conditions, indicating that converting external collaborative resources into innovation outcomes still depends on local capacities to receive and organize those resources. The key factors exhibit four nonlinear response patterns: threshold jumps, sustained growth, initial decline followed by increase, and constraint-related inhibition. These findings clarify the conditions under which institutionally enabled park-based collaboration is associated with stronger innovation capacity in less-developed regions and offer a perspective on the organization, restructuring and evolution of innovation systems in these regions.</p>