The impact of public infrastructure investment on the productive performance of firms has been an important focus of the recent literature on productivity growth. The size of this impact has important implications for policymakers' decisions to invest in public capital, and productivity analysts' evaluation of productivity growth fluctuations and declines. However, detailed evaluation of the infrastructure impact is difficult using existing studies which rely on restricted models of firms' technology and behavior.In this paper we construct a more complete production theory model of firms' production and input decisions. We then apply our framework to state-level data on the output production and input (capital, nonproduction and production labor and energy) use of manufacturing firms to evaluate the contribution of infrastructure to firms' costs and productivity growth. We find that infrastructure investment does provide a significant direct benefit to manufacturing firms and thus augments productivity growth. We also show, however, that this evidence should be interpreted taking into account the social cost of such capital (which is not reflected in firms' costs), and the indirect impact resulting from scale effects.

This article examines the effect of exposure to violent crime on students' standardized test performance among a sample of students in New York City public schools. To identify the effect of exposure to community violence on children's test scores, we compare students exposed to an incident of violent crime on their own blockface in the week prior to the exam to students exposed in the week after the exam. The results show that such exposure to violent crime reduces performance on English language arts assessments and has no effect on math scores. The effect of exposure to violent crime is most pronounced among African Americans and reduces the passing rates of black students by approximately 3 percentage points.

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infrastructure, productivity, externalities,