Doctoral Dissertation Research in Economics: The Diffusion of Automobiles and Motortrucks in the United States in the 20th Century

该奖项全部或部分由《2021年美国救援计划法案》（公法117-2）资助。这篇经济学博士论文考察了20世纪早期和中期汽车和卡车在美国农场的扩散，特别是最后一英里全天候道路通道对这种扩散的影响，以及这种扩散对农业生产力的影响。本文还研究了群体认同对公民和经济主体决策的影响，因为他们考虑发达国家和发展中国家之间充分整合资本、劳动力和贸易流动的协议（就像在欧盟发生的那样）。在美国，汽车和卡车几乎取代了铁路，用于长途客运和货运。传播的速度可能受到全天候道路的影响，而农民是汽车和卡车的早期采用者之一。在今天的欠发达国家，机动车辆的销售有了巨大的增长，但缺乏最后一英里的道路通道减缓了机动车辆在农场的扩散。测量全天候道路通道对汽车和卡车使用的影响，对于可靠地模拟未来的气候模式、世界交通网络、城市增长模式、人口和农业至关重要。衡量汽车和卡车对农业生产力的影响，并将这种影响分解为节省劳动力和节省土地的部分，对于更好地检验希克斯（1932）在农业背景下提出的诱导创新假设至关重要：“生产要素相对价格的变化本身就是发明的刺激，并且是一种特定类型的发明——直接用于节约使用已经变得相对昂贵的要素。”提议的或现有的资本、劳动力和贸易流动自由化的国际协议经常遭到许多潜在签署国公民的政治反对，有时要么不被采纳，要么退出，尽管绝大多数人达成共识，并高度相信这些协议将提高所有签署国的国民收入（以及整个世界经济的总体效率）。理解群体认同对支持或反对经济一体化的政治决策的影响，对于理解欧盟东扩、英国退欧以及在发达国家汹涌而来的各种本土主义运动等事件至关重要。在论文关于道路通道对汽车和机动卡车在农场吸收的影响的章节中，从1929年到1959年的美国农业普查中开发了一个县的面板数据集，这是机动车辆在农场传播最快的时期。在OLS规范中，道路通行作为一个单一变量，具有县和州每年的影响和多重控制，道路通行与机动车的使用率高4.6%和汽车的使用率高2.8%相关。基于多项式空间滞后工具的IV估计表明，道路通行导致机动车的使用率提高3.6%，汽车的使用率提高4.2%。这些平均值掩盖了道路通行影响的巨大异质性。道路通行的影响因一个县生产的作物和农产品的类型而明显不同。在考察汽车和卡车对农业生产力的影响时，将对农场企业的CES-translog、Cobb-Douglas translog（带交互项）和log-log（不带交互项）生产函数进行估计，每个观察值都是单个县的农场企业。每个生产要素的影响将根据县域的作物构成而有所不同。人口、气候和天气控制变量将在县一级进行控制。将考察全要素生产率的变化。汽车和卡车的影响将分别分解为节省劳动力和节省土地的部分。研究群体认同对经济一体化影响的实验是由Agranov和Palfrey（2015）改编的Metzler-Richards劳动供给模型和实现中位数选民定理的投票模型驱动的。人们可能会假设，在群体内情绪更强烈的人群中，所选择的税率会更高，而在给定税率的条件下，更强烈的群体内情绪将导致拥有更高技能劳动力的国家的选民不太可能投票支持一体化。然而，群体内认同对各国选民的一体化投票的最终影响在理论上是不确定的，因为尽管以税率为条件，群体内认同可能导致支持一体化的选票减少，但群体内认同增加了制定的税率，并且在拥有更多熟练劳动力的国家，一个主体投票支持一体化的可能性在税率上增加。实验结果将表明这两种影响中哪一种更大。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

This award is funded in whole or in part under the American Rescue Plan Act of 2021 (Public Law 117-2).This doctoral dissertation in economics examines the diffusion of automobiles and motortrucks on American farms in the early- and mid-20th century – specifically, the impact of last-mile all-weather road access on said diffusion, and the impact of said diffusion on agricultural productivity. This dissertation also examines the impact of group identity on the decisions of citizens and economic agents as they consider agreements to fully integrate capital, labor, and trade flows between a developed country and a developing country (as has occurred in the European Union). In the U.S., automobiles and motortrucks all but replaced railroads for long-distance travel, both passenger and freight. The pace of diffusion was likely powerfully influenced by access to all-weather roads and farmers were among the early adopters of automobiles and motortrucks. In less developed countries today, there is tremendous growth in the sales of motor vehicles, but lack of last-mile road access slows the diffusion of motor vehicles on farms. Measuring the impact of all-weather road access on uptake of automobiles and motortrucks is critical to reliably modelling the future of climate patterns, world transportation networks, urban growth patterns, demographics, and agriculture. Measuring the impact of automobile and motortruck uptake on agricultural productivity and decomposing the impact into a labor-saving and land-saving component, is critical to better examining in the context of agriculture the induced innovation hypothesis posited by Hicks (1932): "a change in the relative prices of the factors of production is itself a spur to invention, and to invention of a particular kind—directed to economizing the use of a factor which has become relatively expensive." Proposed or existing international agreements liberalizing capital, labor, and trade flows are often politically opposed by many citizens of prospective signatory nations, and sometimes either fail to be adopted or are withdrawn from, despite overwhelming consensus and a high degree of confidence that such deals will result in boosts to the national incomes of all signatory nations (and general efficiency gains to the world economy as a whole). Understanding the impact of group identity on political decisions in favor or against economic integration is critical to understanding events such as the eastward expansion of the European Union, the Brexit withdrawal, and various nativist movements surging throughout the developed world.For the dissertation chapter on the impact of road access on automobile and motortruck uptake on farms, a panel data set of counties is developed from U.S. Agricultural Censuses from 1929 to 1959, the period of most rapid diffusion of motor vehicles on farms. In OLS specifications with road access as a single variable with county and state-by-year effects and multiple controls, road access was associated with usage rates that were 4.6% higher for motortrucks and 2.8% higher for automobiles. IV estimation based on a polynomial spatial-lag instrument indicates that road access caused usage rates to be 3.6% higher for motortrucks and 4.2% higher for automobiles. These averages disguise a great deal of heterogeneity in the effect of road access. The impact of road access differed markedly by the types of crops and farm products produced in a county. When examining the impact of automobiles and motortrucks on agricultural productivity, a CES-translog, a Cobb-Douglas translog (with the interaction terms), and a log-log (without the interaction terms) production function of farm enterprises will be estimated, with each observation being the farm enterprises in a single county. The effect of each factor of production will be allowed to vary based on the crop composition of the county. Demographic, climate, and weather control variables will be controlled for at the county level. Changes in total factor productivity will be examined. The impact of automobiles and motortrucks will separately be decomposed into labor-saving and land-saving components. The experiment examining the impact of group identity on economic integration is motivated by the Metzler-Richards labor supply model as adapted by Agranov and Palfrey (2015) and a voting model that actualizes the Median Voter Theorem. One may hypothesize that taxation rates selected would be higher among populations with stronger in-group sentiment, and that conditional on a given taxation rate stronger in-group sentiment will cause the electorates of countries with higher-skilled workforces to be less likely to vote in favor of integration. However, the ultimate impact of in-group identity on the integration vote of the electorates of countries is theoretically indeterminate, as although conditional on a taxation rate in-group identity may cause fewer votes to be in favor of integration, in-group identity increases the tax rate enacted and the likelihood of a subject in countries with more-skilled workforces voting for integration is increasing in the tax rate. The results of the experiment will show which of these two effects is greater.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.