Book excerpt: The focus of this thesis is on issues of empirical industrial organization. Specifically, I utilize tools and ideas from Industrial organization to study areas of health and history. In Chapter 1, I examine the relationship between how hospital ownership is organized and the intensity of competition in the US health care market. I study the question using an empirical entry model. These models typically exhibit multiple equilibria. To resolve this problem, a novel algorithm that computes all the equilibria of the game is developed. My findings suggest that for-profit and not-for-profit hospitals can be regarded as supplying differentiated products. I also find evidence suggesting that markets that have both types of hospitals enjoy a higher level of health care services. Chapter 2 is coauthored with Eugene Choo. In this chapter, we investigate the variation of winning bids in slave auctions held in New Orleans from 1804 to 1862. Specifically, we measure the variation in the price of slaves conditional on their geographical origin. Previous work using a regression framework ignored the auction mechanism used to sell slaves. This introduces a bias in the conditional mean of the winning bid. Unfortunately, the number of bidders is unobserved by the econometrician. We adopt the standard framework of a symmetric independent private value auction and propose an estimation strategy to overcome this bias. We find the number of bidders had a significant positive effect on the average winning bid. The price variation according to the geographical origin of slaves found in earlier work continued to persist after accounting for the omitted variable. Chapter 3 is coauthored with Henry Overman, Diego Puga, and Matthew Turner. In this chapter, we study the relationship between urban sprawl and obesity. Using data that tracks individuals over time, we find no evidence that urban sprawl causes obesity. We show that previous findings of a positive relationship most likely reflect a failure to properly control for the fact the individuals who are more likely to be obese choose to live in more sprawling neighborhoods. Our results indicate that current interest in changing the built environment to counter the rise in obesity is misguided.