The importance of business travel for trade: Evidence from the liberalization of the Soviet airspace
利用苏联领空自由化这一自然实验，发现商务旅行成本下降显著促进了欧洲与东亚之间的贸易，表明面对面交流是解释距离与贸易负相关的重要因素。
The strong negative relationship between geographical distance and trade is not well understood. I use the liberalization of the Soviet airspace to estimate the causal impact of business travel cost on trade. The liberalization radically reduced travel time between Europe and East Asia and was followed by a significant increase in trade. I find that the cost of business travel can account for a large share of the trade frictions that cause trade to sharply decline with distance. A plausible explanation for these results is that face-to-face interaction through business travel is important for trade.