经济学家发现，从长期来看，美国的经济增长不一定会从数十亿美元的公路建设支出中受益。One of the few things that Democrats and Republicans agree on is that spending billions of dollars on America’s roads would boost productivity and the U.S. economy’s growth prospects. Economists aren’t so sure. A wide body of research focused on the effects of highway spending suggests that major new investment in U.S. roads would generate little, if any, long-term economic gain.在民主党和共和党达成共识的为数不多的几件事中，有一件是美国在公路建设上投入数十亿美元将提高生产率，提振美国经济增长预期。经济学家并不这么肯定。大量关于高速公路支出影响的研究表明，即使对美国公路的重大新投资会产生长期经济收益，该收益也很少。While the projects would spur hiring and spending temporarily, both when thy are announced and under way, they aren’t likely to raise the economy’s productivity and, in turn, its overall growth potential in a lasting way, many researchers find. That is because the U.S. already has an extensive system of roads, so building more wouldn’t add much to productivity, economists say.许多研究人员发现，虽然这些项目在宣布和实施时都会暂时刺激就业和支出，但它们不可能持续提高经济生产力，进而也不可能提高其整体增长潜力。经济学家说，这是因为美国已经有一个广泛的公路系统，所以建设更多的公路也不会给生产力带来多大的提高。New spending for roads accounts for the largest single share—roughly 19%—of the $579 billion in new spending that the White House and a group of lawmakers have agreed to. Both Democrats and Republicans say that money would raise the economy’s productivity, defined as the level of output per hour worked.在白宫和一些立法者已经同意的5790亿美元的新支出中，道路建设占了最大的份额，约为19%。民主党和共和党都表示，这笔支出将提高经济生产率，即每小时的经济产出水平。Development of the U.S. interstate highway system between the 1950s and 1970s—currently 47,000 miles of multilane highways stretching coast to coast—did make the economy much more productive, John Fernald, an economist at the Federal Reserve Bank of San Francisco, wrote in a 1999 paper.旧金山联邦储备银行的经济学家约翰·弗纳德在1999年的一篇论文中写道，20世纪50年代至70年代美国州际公路系统的发展——目前47,000英里的多车道沿海岸公路——确实使经济生产力大大提高了。The system meant a cross-country trip that used to take months could be accomplished in days. Businesses gained access to new suppliers and new customers. Cities were able to specialize in certain industries. International trade opened up. By one estimate, the U.S. economy would be 3.9% smaller today without the interstate highway system. But those gains all came about when the highways were built. By now, the gains have been reaped. “Building the interstate highway system was enormously productive,” Mr. Fernald said. “That does not imply that building a second one would be equally productive.”这样的公路系统意味着，过去需要花费几个月时间的全国旅行在几天内就可以完成。企业能接触到新的供应商和新客户。一些城市可以专门从事某些特定行业。国际贸易开放了。据估计，如果没有州际高速公路系统，今天的美国经济规模将减少3.9%。但这些收益都是在高速公路建成后产生的。到目前为止，这些收益已被收入囊中。弗纳尔德说，“建设州际公路系统的效率非常高。”“这并不意味着建造第二个公路系统也会有同样的效果。”本文节选自：The Wall Street Journal（华尔街日报）
发布时间：2021.07.04
作者：WSJ.com: US Business
原文标题：Why More Highway Spending Won't Rev Up the Economy
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