Why high-speed rail causes heterogeneous spatial patterns in firm innovation: Perspectives from intensive and extensive margins

This study examines the impact of high-speed rail (HSR) on corporate innovation in China, analyzing county-level patent applications. Utilizing difference-in-differences regression, we break down the overall impact of HSR connectivity on innovation into two categories: extensive margins, where a greater number of firms become innovative, and intensive margins, where individual firms increase their level of innovation. HSR access has increased patent applications, particularly in manufacturing and non-high-tech services, affecting both margins. However, in high-tech services, the impact is significant only on the extensive margin. Effects vary between urban areas and peripheral counties, with knowledge spillovers and brain drain as key predictors.