Cities, Trade and Productivity

近年来，随着从大衰退中相对缓慢的复苏，贸易和地区政策一直是许多国家公开辩论的中心。特别是，在美国和英国等发达经济体，相当一部分公众已开始支持将更具保护主义色彩的国际贸易政策与更激进的“以地为本”政策相结合，旨在减少不同地区和不同国家人民之间的不平等。在此背景下，拟议的研究旨在通过研究影响贸易流动的力量与国内经济地理决定因素之间的相互作用，为围绕最佳地理和国际贸易政策的辩论提供信息。我们相信，更好地了解这些力量将有助于制定一系列政策领域的政策，包括贸易、城市规划和区域凝聚力政策。理论和最近的经验发现表明，我们应该预料到贸易和国内经济地理之间的重要互动。最近对国际贸易的研究证实，贸易自由化通过允许规模较大、生产率较高的公司以牺牲较小、生产率较低的公司为代价来增长，从而提高了整体生产率。来自城市经济学的证据表明，这些生产性企业往往聚集在最大、生产率最高的城市和地区。综上所述，这些发现让我们预计，贸易自由化可能会对各国内部的地区差异产生重大影响。同样，旨在在国家内部城市和地区之间重新分配经济活动的空间政策，如旨在提振落后地区的就业补贴，可能会影响资源的重新分配，以应对贸易政策的变化。反过来，这可能对国际贸易收益的规模和分配产生重要影响。我们计划分三个步骤进行。首先，我们计划通过对出口、进口和国内贸易流动的地理位置进行全面的实证分析来确定关键事实。我们的主要目标将是了解那些倾向于出口很大比例的产出或在总消费中很大程度上依赖进口的城市和地区的特征。这些地区可能最直接地受到影响国际贸易流动的冲击的影响，例如贸易政策的变化或与正在进行的新冠肺炎大流行相关的限制。其次，我们将开发能够解释数据中发现的关键规律的模型，重点放在进出口的地理位置上。最后，我们计划将理论与丰富的数据结合起来，分析现实的政策情景。我们计划研究贸易开放对生产率和福利的影响，以确定在分析中加入内部地理因素是否会实质性地改变我们对贸易收益的估计。我们还计划评估旨在解决地区差距的政策的经济影响，以及限制成功地点增长的规划限制的影响。在进行这些分析时，我们将以两个关键目标为指导。首先，我们的目标是展示这些政策在对国际贸易开放的经济体环境中的影响与以前侧重于封闭经济体的工作有何不同。其次，我们将分析这些地区性“拉平”政策的影响如何随感兴趣国家的贸易开放程度而变化。这将使我们能够回答一些问题，如成功城市的限制性规划是增加还是减少贸易自由化的好处；或者对贸易开放是否会增加旨在减少国内地区不平等的政策的成本。

Trade and regional policies have been at the centre of public debate in many countries in recent years, as the relatively slow recovery from the Great Recession has unfolded. In particular, substantial sections of the public in advanced economies such as the US and the UK have started to support a combination of more protectionist international trade policies and more aggressive "place based" policies aimed at reducing inequality both across places and across people within their countries. Against this backdrop, the proposed research aims to inform the debate surrounding optimal geographic and international trade policies by studying the interactions between the forces that shape trade flows and the determinants of within-country economic geography. We believe an improved understanding of these forces will prove useful for policy design across a number of policy areas, including trade, urban planning and regional cohesion policies. Theory and recent empirical findings suggest that we should expect important interactions between trade and internal economic geography. Recent research in international trade has established that trade liberalisation raises overall productivity by allowing larger, more productive firms to grow at the expense of smaller, less productive ones. Evidence from urban economics suggests that these productive firms tend to cluster together in the largest and most productive cities and regions. Taken together, these findings lead us to expect that trade liberalisations may have a substantial impact on regional disparities within countries. Equally, spatial policies that aim to reallocate economic activity across cities and regions within countries, such as employment subsidies aimed at boosting lagging regions, are likely to influence the reallocation of resources in response to changes in trade policy. In turn, this can have important implications for the size and distribution of the gains from international trade.We plan to proceed in three steps. First, we plan to establish the key facts by conducting a comprehensive empirical analysis of the geography of exporting, importing and within country trade flows. Our main aim will be to understand the defining characteristics of cities and regions that tend to export a large share of their output or rely on imports for a large share of their overall consumption. These locations are likely to be most directly affected by shocks affecting international trade flows, such as changes in trade policy or restrictions associated to the ongoing Covid-19 pandemic. Second, we will develop models that can explain the key regularities uncovered in the data, with a particular focus on the geography of importing and exporting. Finally, we plan to combine theory with rich data to analyse realistic policy scenarios. We plan to study the implications of trade openness for both productivity and welfare, with a view to determining whether the addition of internal geography to the analysis materially changes our estimates of the gains from trade. We also plan to assess the economic implications of policies aimed at tackling regional disparities, as well as the effects of planning restrictions that constrain the growth of successful locations. When performing these analyses, we will be guided by two key objectives. Firstly, we will aim to showcase how the effects of these policies differ in settings where economies are open to international trade as compared to previous work that focuses on closed economies. Secondly, we will analyse how the effects of these regional "levelling up" policies vary with the degree of trade openness in the countries of interest. This will allow us to answer questions such as whether restrictive planning in successful cities increases or decreases the benefits of trade liberalisation; or whether opening up to trade increases the cost of policies aimed at reducing within country regional inequalities.