Econ Papers Daily / 期刊论文
评估港口拥堵对美国农产品出口的延迟效应
Assessing the Day Delay Effect of Port Congestion on US Agricultural Exports
摘要
Relative to the rest of the world, shipping delays have been a problem in the US even prior to COVID‐19 but became more publicized and exacerbated during the pandemic. While previous studies have focused on COVID‐19 shocks using event study methods, we quantify the effect of congestion, measured as the average number of days a vessel spends in port, on US agricultural container exports using monthly export data from US ports. We estimate, in general, that a one‐day increase in congestion reduces containerized US agricultural exports by 2.5% in quantity and 1.1% in value. This quantity effect is comparable to an ad‐valorem tariff of roughly 12%–17% points. Container congestion reduces monthly exports of agricultural products by 77 thousand metric tons and $43.6 million during the pre‐pandemic period 2016–2019. For 2020–2021, these losses increase to 228 thousand metric tons and $111 million. Western ports, in particular, experience the most pronounced losses across all regions, especially on bulk commodity exports with an average monthly loss of $89.0 million after the pandemic and $26.3 million for the pre‐pandemic level. After the pandemic, the total loss in quantity of Western ports accounts for about 90% of the sum of all US ports, and the loss in value for about 70%.
中文摘要
相对于世界其他地区，美国在新冠疫情之前就已存在航运延误问题，但在疫情期间该问题受到更多关注并进一步加剧。以往研究多采用事件研究法聚焦新冠疫情冲击，而我们利用美国港口的月度出口数据，量化了拥堵（以船舶在港平均停留天数衡量）对美国农产品集装箱出口的影响。我们总体估计，拥堵每增加一天，美国集装箱农产品出口量减少2.5%，出口额减少1.1%。这一数量效应大致相当于12%–17个百分点的从价关税。在2016–2019年疫情前时期，集装箱拥堵使农产品月度出口减少7.7万公吨和4360万美元。2020–2021年，这些损失增至22.8万公吨和1.11亿美元。西部港口在所有地区中损失尤为突出，尤其是大宗商品出口，疫情后月均损失8900万美元，疫情前水平为2630万美元。疫情后，西部港口数量损失约占美国所有港口总和的90%，价值损失约占70%。