State and local governments implement many policies to address issues or solve problems within their jurisdictional boundaries. Areas within the purview of state and local government policymaking include public-health-related activities like smoking and drinking, as well as policies related to the criminal justice system. These policies often have unintended (or intended) spillover effects, both in terms of externalities and spatial spillovers to nearby jurisdictions. In this dissertation I examine three different policies or innovations that were implemented at the state or local level: smoking bans in bars and restaurants, ban-the-box policies, and the introduction of ridesharing services. In Chapter 1 I examine the impact of smoking bans in bars and restaurants on the amount and location of alcohol consumption, smoking status, and the incidence of alcohol-related externalities such as drunk driving and violent crime. I exploit differential timing in the adoption of these smoking bans across state and local jurisdictions between 2004 and 2012. I find that smoking bans in bars and restaurants lead to an increase of one drink per month, on average, for individuals who drink alcohol. These increases are concentrated among occasional and former smokers. Smoking bans do not have an effect on whether individuals smoke during my sample period. I also do not find effects of smoking bans on violent crime, but there is a 4% increase in fatal drunk-driving crashes in areas with a high prevalence of smoking. These results imply that smoking bans in bars and restaurants lead to unintended consequences in the form of increased alcohol consumption and drunk driving. In Chapter 2 my coauthor and I revisit the labor market effects of ban-the-box policies, which are policies that prevent employers from asking job applicants about their previous contact with the criminal justice system. These policies are intended to reduce the stigma associated with incarceration, so as to help individuals who were recently incarcerated get their "foot in the door" to find formal-sector employment. Some of the existing research on BTB policies, however, finds that these policies lead to broad discrimination against young, non-college-educated minority men (the groups employers may believe to be most likely to have had prior contact with the criminal justice system). Using variation in exposure to these policies both within and across metropolitan statistical areas, we find no evidence of discrimination and evidence of positive employment effects for some subgroups of Hispanic men. In Chapter 3 I analyze how the introduction of ridesharing services such as Uber and Lyft into the most populous U.S. cities affected fatal motor vehicle crashes, particularly drunk-driving-related crashes. I exploit the differential introduction of Uber and Lyft into these cities during the time period 2006 to 2016. I find small declines in drunk-driver-related fatal motor vehicle incidents and small increases in overall fatal motor vehicle incidents, but I am unable to reject the null hypothesis of no effect of Uber or Lyft on these outcomes. Event studies indicate that both drunk-driver-related and overall fatal motor vehicle incidents decline over the medium-to-long term, which is consistent with both a delayed adoption of this new transportation option by riders and or drivers, and with returns to experience in driver skill for Lyft or Uber drivers.