Does Smart City Policy Widen the Urban–Rural Income Gap? Evidence from the Yangtze River Delta Using a Double Machine Learning Approach

The urban–rural income gap remains a major obstacle to achieving common prosperity and poses a key challenge for developing countries undergoing modernization. Smart city initiatives may reshape wealth creation and income distribution while promoting urban development. Using panel data for 41 prefecture-level cities in the Yangtze River Delta from 2003 to 2024, and employing a double machine learning approach, this study takes the smart city pilot policies as a quasi-natural experiment to assess the impact of smart city pilot policies on the urban–rural income gap. The results indicate that the policy has overall widened the urban–rural income gap in treated cities. This effect is achieved by enhancing urban innovation resilience and promoting industrial structure upgrading, which in turn further boost urban residents’ income. Notably, in regions with higher levels of human capital and greater outward openness, the income-widening effect of the policy becomes statistically insignificant and even exhibits a tendency to narrow the urban–rural income divide. Furthermore, a spatial spillover analysis reveals that the policy’s impact exhibits significant spatial spillover characteristics. These findings provide empirical evidence and policy insights for refining smart city pilot policies and accelerating the advancement of common prosperity.