The advent of the U.S. Interstate Highway System provides an interesting experiment, which I use to identify the labor market effects of reduced trade barriers. This highway network was designed to connect cities and border crossings and to serve national defense, and as an unintended consequence it crossed many rural counties. I find that these counties experienced an increase in trade-related activities, such as trucking and retail sales. By increasing trade, the highways raised the relative demand for skilled manufacturing workers in skill-abundant counties and reduced it elsewhere, consistent with the predictions of the Heckscher-Ohlin model.

We analyze for the first time the economic contributions of modern industrial robots, which are flexible, versatile, and autonomous machines. We use novel panel data on robot adoption within industries in seventeen countries from 1993 to 2007 and new instrumental variables that rely on robots’ comparative advantage in specific tasks. Our findings suggest that increased robot use contributed approximately 0.36 percentage points to annual labor productivity growth, while at the same time raising total factor productivity and lowering output prices. Our estimates also suggest that robots did not significantly reduce total employment, although they did reduce low-skilled workers’ employment share.

Since the early 1990s, recoveries from recessions in the US have been plagued by weak employment growth. One possible explanation for these "jobless" recoveries is rooted in technological change: middle-skill jobs, often involving routine tasks, are lost during recessions, and the displaced workers take time to transition into other jobs (Jaimovich and Siu, 2014). But technological replacement of middle-skill workers is not unique to the US – it also takes place in other developed countries (Goos, Manning, and Salomons, 2014). So if jobless recoveries in the US are due to technology, we might expect to also see them elsewhere in the developed world. We test this possibility using data on recoveries from 71 recessions in 28 industries and 17 countries from 1970-2011. We find that though GDP recovered more slowly after recent recessions, employment did not. Industries that used more routine tasks, and those more exposed to robotization, did not recently experience slower employment recoveries. Finally, middle-skill employment did not recover more slowly after recent recessions, and this pattern was no different in routine-intensive industries. Taken together, this evidence suggests that technology is not causing jobless recoveries in developed countries outside the US.

We test the hypothesis that information and communication technologies (ICT) polarize labor markets by increasing demand for the highly educated at the expense of the middle educated, with little effect on low-educated workers. Using data on the United States, Japan, and nine European countries from 1980 to 2004, we find that industries with faster ICT growth shifted demand from middle-educated workers to highly educated workers, consistent with ICT-based polarization. Trade openness is also associated with polarization, but this is not robust to controlling for R&D. Technologies account for up to a quarter of the growth in demand for highly educated workers.

Africa?s demand for urban housing is soaring, even as it faces a proliferation of slums. In this setting, can modest infrastructure investments in greenfield areas where people subsequently build their own houses facilitate long-run neighborhood development? We study Sites and Services projects implemented in seven Tanzanian cities during the 1970s and 1980s, and we use a spatial regression discontinuity design to compare greenfield areas that were treated (de novo) with nearby greenfield areas that were not. We find that by the 2010s, de novo areas developed into neighborhoods with larger, more regularly laid-out buildings and better-quality housing.