River deep, mountain high: of long run knowledge trajectories within and between innovation clusters
研究将地理集群与技术轨迹结合，分析美国发明集群间的长引用链，发现知识通过全球管道在集群间流动，而技术轨迹的中间节点跨越长距离。
We bring together the topics of geographical clusters and technological trajectories, and shift the focus of the analysis of regional innovation to main technological trends rather than firms. We define a number of inventive clusters in the US space and show that long chains of citations mostly take place between these clusters. This is reminiscent of the idea of global pipelines of knowledge transfer that is found in the geographical literature. The deep citations are used to identify technological trajectories, which are the main directions along which incremental technological progress accumulates into larger changes. While the origin and destination of these trajectories are concentrated in space, the intermediate nodes travel long distances and cover many locations across the globe. We conclude by calling for more theoretical and empirical attention to the ‘deep rivers’ that connect the ‘high mountains’ of local knowledge production.