In the first chapter of this dissertation I present evidence with the goal of explaining the relationship between access to public transportation and school choice. One of the goals of school choice is to allow parents to send their children to higher-performing schools. Several studies have shown that distance to school is one of the main determinants of school choice, but challenges to address endogeneity issues remain. This chapter examines school choice in a context where vouchers have been implemented on a large scale and combines that analysis with a natural experiment to address the endogeneity concern posed above. In particular, I use information from Santiago, Chile, and take advantage of the construction of a new subway line that crosses a large area of the city previously unconnected to the subway network. I provide convincing evidence to show that the introduction of the subway line was arguably exogenous for families living close to the new subway stations. The high clustering of schools in certain areas of the city makes distance especially relevant for students who live in neighborhoods with little connectivity to transport networks. The use of rich administrative data allows me to calculate the distance from students’ homes to each school in the city with high accuracy. Using an independent cross-sample difference-in-difference estimation, I find that (i) students near the new subway stations travel significantly farther to school than students who live in nearby areas with no subway stations, and (ii) that students near the subway are willing to travel farther to attend schools that perform better in standardized tests. This set of results is particularly informative for the ongoing school-choice debate, reconciling the advocates’ and skeptics’ views in the sense that school choice may lead to higher-performing schools once access restrictions are eased. In the second chapter, I present causal evidence of the relationship between cell phone use and traffic accidents. Since drivers have incentives to underreport their cell phone use, and this behavior is not captured by official statistics, the magnitude of the problem is not known with certainty. In this chapter, I take advantage of a government program implemented in Chile between 2010 and 2012, which connected rural areas to the mobile phone network for the first time. I employ two alternative differences-in-differences estimation strategies to produce a causal estimate of the impact of cell phone use on traffic accidents. As a first strategy, I take advantage of the phasing in of the program to compare localities treated in the first phase of the program with localities treated at a later stage. As a second strategy, I use GIS to generate and select random polygons in areas that already had cell phone coverage before the program started, and use these random areas as a control group for areas treated by the program. Both strategies lead to similar results. I find that the availability of cell phone coverage in a locality causes an increase of almost 30% in the number of accidents, which is consistent with the widespread and frequent cell phone use by drivers reported in several studies. This gives an indication that policy makers should approach the problem of cell phone use by drivers with the same or more urgency than they have approached other issues such as drunk driving. In the third and final chapter, I examine the relationship between subway access and employment in areas surrounding subway stations. Although subways represent considerable investments and their construction often creates substantial disruptions to urban life, little is known about the effects of subway lines on firms located in the neighborhoods surrounding the stations. In this chapter, I look into the effect on employment of the opening of a new subway line in Santiago that connected several densely populated neighborhoods to the larger subway network. For this purpose, I take advantage of highly detailed yearly administrative data on all firms operating within the city between the years 2005 and 2009. Using an empirical strategy based on the geographic distance between firms and the new subway stations, I find no significant effect of the subway on employment in firms close to the stations. The one exception is a significant increase in employment related to real estate activities.