Using Canadian administrative data, I study the careers of young entrepreneurs and the heterogeneity among them. I investigate both the mechanisms that drive entry into entrepreneurship and the determinants of entrepreneurial success. Empirically, entrepreneurs who have previously worked in high-wage firms tend to do better. I explain this finding using a dynamic model of career choice that features heterogeneous employers, human capital accumulation, and unobserved heterogeneity across individuals. Among other things, I find that prior work experience is particularly valuable for relatively low ability individuals. I use the estimated model to evaluate policies designed to promote entrepreneurship.

Using Canadian administrative data, this paper presents evidence of revenue and productivity spillovers across firms at fine spatial scales. Accounting for the endogenous sorting of firms across space, we estimate an average elasticity of firm revenue and productivity with respect to the average quality of other firms within 75 meters of 0.024. We find scant evidence that the average firm benefits from being surrounded by a greater amount of economic activity at this spatial scale. Sorting of higher quality firms into more productive locations and higher average and aggregate quality peer groups is salient in the data.

We investigate the effect of subway system openings on urban air pollution. On average, particulate concentrations are unchanged by subway openings. For cities with higher initial pollution levels, subway openings reduce particulates by 4 percent in the area surrounding a city center. The effect decays with distance to city center and persists over the longest time horizon that we can measure with our data, about four years. For highly polluted cities, we estimate that a new subway system provides an external mortality benefit of about $1 billion per year. For less polluted cities, the effect is indistinguishable from zero. Back of the envelope cost estimates suggest that reduced mortality due to lower air pollution offsets a substantial share of the construction costs of subways.

We investigate how containerization impacts local economic activity. Containerization is premised on a simple insight: packaging goods for waterborne trade into a standardized container makes them cheaper to move. We use a novel cost-shifter instrument---port depth pre-containerization---to contend with the non-random adoption of containerization by ports. Container ships sit much deeper in the water than their predecessors, making initially deep ports cheaper to containerize. We find that counties near containerized ports grew twice as rapidly as other coastal port counties between 1950 and 2010 because of containerization. Gains are concentrated in areas with initially low land values.