Transportation Infrastructure and Digital Economy—Evidence from Chinese Cities

In this research, the influences of railways, roads, waterways, and civil aviation on the digital economy were analyzed using traffic, urban, and enterprise data in the integrated transport system. Regression was performed through the generalized spatial least square method (GS2SLS) in the empirical section to solve the endogeneity problem. It was verified that transportation infrastructure can promote the digital economy. While the development of railways, waterways, and roads is expected to rise by 1%, the digital economy will be increased by 0.0049, 0.0048, and 0.0031, respectively, and civil aviation’s effect is not significant. The robustness test results were still remarkable. From the industry level of cities, it was found that transportation infrastructure mainly promotes the development of the digital economy by upgrading the industrial structure. At the enterprise level, promoting entrepreneurship and facilitating the digital transformation of enterprises have become the main driving forces for the development of the digital economy, and strengthening labor flow is a vital promotion mechanism at the factor level of cities. In addition, a significant single-threshold effect is observed in promoting the digital economy by transportation infrastructure. In the cities that cross the threshold of the economic development level, the progress in the digital economy increases from 0.0027 and 0.0035 to 0.0059 and 0.0061 for 1% development of railways and roads; the promotion of the digital economy by transportation infrastructure is more evident in cities with a permanent-residents population of more than 3 million. Developing the digital economy and transport infrastructure is essential for economic recovery and sustainable development.