The Macroeconomic Consequences of Infrastructure Investment

Valerie A. Ramey

NBER Working Paper No. 27625
Issued in July 2020
NBER Program(s):Economic Fluctuations and Growth, Public Economics

Can greater investment in infrastructure raise U.S. long-run output? Are infrastructure projects a good short-run stimulus to the economy? This paper uses insights from the macroeconomics literature to address these questions. I begin by analyzing the effects of government investment in both a stylized neoclassical model and a medium-scale New Keynesian model, highlighting the economic mechanisms that govern the strength of the short-run and long-run impacts. The analysis confirms earlier findings that the implementation delays inherent in infrastructure projects reduce short-run multipliers in most cases. In contrast, long-run multipliers can be sizable when government capital is productive. Moreover, these multipliers are greater if the economy starts from a point below the socially optimal amount of public capital. Turning to empirical estimation, I use the theoretical model to explain the econometric challenges to estimating the elasticity of output to public infrastructure. Using both artificial data generated by simulations of the model and extensions of existing empirical work, I demonstrate how both general equilibrium effects and optimal choice of public capital are likely to impart upward biases to output elasticity estimates. Finally, I review and extend some empirical estimates of the short-run effects, focusing on infrastructure spending in the ARRA.

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Acknowledgments and Disclosures

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Document Object Identifier (DOI): 10.3386/w27625

Forthcoming: The Macroeconomic Consequences of Infrastructure Investment, Valerie A. Ramey. in Economic Analysis and Infrastructure Investment, Glaeser and Poterba. 2020