This study explores the dynamic and regional effects of highway development on market integration within China’s Yangtze River Economic Belt (YREB), a region of strategic economic importance. Spanning 11 provinces and contributing nearly half of China’s GDP, the YREB faces challenges of uneven development and market segmentation. Highways, as crucial transportation infrastructure, are posited to enhance market integration by reducing costs, improving connectivity, and fostering trade and labor mobility. Utilizing econometric modeling and spatial analysis, the study examines both the nonlinear and heterogeneous impacts of highways on regional integration. Results reveal that highway development significantly promotes market integration, particularly in the short term. However, its marginal effects diminish over time as networks approach saturation. Moreover, highways disproportionately benefit economically advanced and less geographically rugged regions, exacerbating core-periphery disparities. The study identifies critical factors influencing these outcomes, including economic development levels, geographic conditions, and infrastructure saturation. The findings underscore the dual role of highways in fostering connectivity and reinforcing regional inequalities. Policy recommendations emphasize targeted infrastructure investments in underdeveloped areas, integration of highway projects with broader economic policies, and phased infrastructure development strategies to optimize returns and address regional disparities. This research advances understanding of the economic effects of transportation infrastructure, providing theoretical and practical insights for fostering equitable growth and market integration in regional economies.

Highway construction reduces the production costs of enterprises, which is conducive to their increased investment in environmental management and the adoption of green production technologies, thereby promoting regional green economic growth. Traditional research mainly focuses on the pollution problem in the transportation infrastructure and transportation process, and it is difficult to explain the spatial spillover problem of the green economy brought by transportation. We measured the shortest passage time and market access of the Yangtze River Economic Belt highway from 2005 to 2019. Meanwhile, we measured the green total factor productivity based on the Malmquist-Luenberger index. The empirical results show that highway construction has a significant role in promoting green economic growth in the Yangtze River Economic Belt. However, there is obvious regional heterogeneity in the degree of effect. Market access has the largest effect in large cities, followed by medium cities, and has the smallest effect on small cities. This suggests that there is an environmental “bottoming-out effect” in highway-induced industrial transfer. Further, we find that green technology innovation is the mechanism by which highways affect green economic growth.