Research on the Impact of Digital Infrastructure Construction on High Quality Development of Urban Economy

Abstract

Accurately assessing the true driving effect of digital infrastructure on high-quality urban economic development and identifying its pathways and spatial spillover characteristics are critical issues that urgently need to be addressed. Against this backdrop, this paper first constructs an evaluation system for high-quality urban economic development from five dimensions, and uses the entropy-weighted TOPSIS method to calculate the high-quality development index of 283 prefecture-level cities from 2011 to 2020. Next, using the "Broadband China" pilot project as a quasi-natural experiment, multi-period DID is employed to identify causal effects, and topographic relief and historical post office density are introduced as instrumental variables to handle endogeneity. Then, a spatial Durbin model is constructed to decompose local direct effects and neighboring indirect effects. Finally, the three-step mediation method and causal forest algorithm are used to examine the transmission mechanism and uncover heterogeneity. The results show that digital infrastructure construction increased the urban high-quality development index by 6.8% (β=0.068, p<0.01); the direct effect was 0.284, and the indirect effect was -0.117, exhibiting a "local promotion, neighboring area inhibition" characteristic; the mediating effect accounted for 40.0%, with central cities (0.338) and old industrial bases (0.358) benefiting more significantly. This paper provides empirical evidence for accurately verifying the effects of digital infrastructure construction policies.