This paper uses the historical experience of U.S. states to examine the reasons why energy intensity has declined in some places more than in others. In aggregate, U.S. energy per dollar of GDP declined 34 percent between 1997 and 2018, but across states the decline varied from 9 percent in Iowa to 52 percent in Washington State. I show that none of this variation is explained by either deindustrialization or the changing composition of states’ industrial sectors. Although some U.S. state policies are significantly correlated with these changes, they are not correlated in a way that explains the changing overall state energy intensities. Energy intensity declines do not appear to be a result of leakage to other states or countries and have not been associated with slower economic growth.

本文利用美国各州的历史经验来考察某些地区的能源强度下降幅度大于其他地区的原因。总体而言，1997年至2018年间，美国每美元GDP的能源下降了34％，但各州的下降幅度从爱荷华州的9％到华盛顿州的52％不等。我表明，这种变化都不能通过去工业化或州工业部门组成的变化来解释。尽管美国的某些州政策与这些变化显着相关，但它们并未以解释总体州能源强度变化的方式相互关联。能源强度下降似乎并非泄漏到其他州或国家的结果，并且与经济增长放缓无关。