Role of Hub Firms in Geographical Transaction Network

In this study, we investigate the role of geographical proximity in an inter-firm transaction network and the role of hub firms on geographical spread of regional impact. By using inter-firm micro transaction data of over 800 thousands firms, we found that indirect transaction is geographically dispersed mainly due to a few hub firms, although firm's direct transactions mostly occur within geographically narrow areas. More precisely, median distance between indirect transaction partners (partners' partners) is 255km, which is much larger than that between direct transaction partners (29km). In a counterfactual transaction network without hub firms, whose transaction relations are no less than 100, median distance between indirect transaction partners is reduced to 70km, thereby suggesting the important role of hub firms in a geographical transaction network. We confirm this suggestion through an analysis of regional impact of the Great East Japan Earthquake.