The Equipment Hypothesis and U.S. Economic Growth

In several articles published in the 1990s, de Long and Summers argued that investment in producer durables had a high propensity to generate externalities in using industries, resulting in a systematic and substantial divergence between its social and private return. They maintained, moreover, that this was not the case for structures investment. Together, these claims constitute the equipment hypothesis. This paper explores the degree to which the history of U.S. economic growth in the twentieth century supports it