We use a recent survey of college (American) football fans to study rivalry, where we find the most intense rivalries occur between in-state teams. Relatedly, within a conference fans are more likely to target rivalrous feelings toward the winningest teams and, in Bowl Championship Series conferences, teams who have been conference members for a longer proportion of time. While the stakes are different from other settings, such as warring nations, college football teams compete for resources and often have loyal followings with strong emotional ties. Thus, examining rivalrous feeling in this setting provides insights into rivalry more generally besides being of interest in its own right as college football is a multi-billion dollar industry. (JEL L22, L83) I. INTRODUCTION For millions of Americans, Saturdays in the fall are synonymous with college (American) football. College football has a pageantry all its own as people gather in groups, sometimes in excess of 100,000, to cheer for their team and socialize even though many fans have no real connection to the university. On the field the teams compete to win games and over the course of a season teams compete to win their conference title. However, many fans do not view all opponents in the conference in the same way--games against some opponents are considered more important irrespective from their impact on conference standings. For example, the University of Arizona and Arizona State University have played for the Territorial Cup for over 100 years. (1) Similarly, the University of Wisconsin and the University of Minnesota compete for Paul Bunyan's Axe while the University of Alabama and the University of Tennessee play on "the third Saturday in October." (2) Sanford and Scott (2014) find that fans are willing to pay higher ticket prices for rivalry games and these games generate significant television revenue. Despite the amateur status of the players, college football is an $8 billion industry. (3) Several high profile teams are valued at over $100 million dollars each (Brewer et al. 2011). Team revenue comes from a variety of sources (television rights, merchandising, fan support, etc.) and on the field success and profit are connected through these channels. In addition, teams find themselves repeatedly battling over the resources needed to compete on the field, namely players and coaches. In this sense, football rivalries are similar to rivalries between siblings, firms, or nations. Sibling rivalries form when children compete for scarce resources (financial, attention, etc.) from their parents (Garg and Morduch 1998; Morduch 2000). The "cola wars" between Coke and Pepsi and the "diaper wars" between Kimberly-Clark and Procter & Gamble arise because these comparable companies offer slightly differentiated products in the same markets. Rivalries between warring nations also often involve prolonged competition over scarce resources (Goertz and Diehl 1993; Klein, Goertz, and Diehl 2006). Rivalry is a subjective phenomenon (Kilduff, Elfenbein, and Staw 2010), but it has an identifiable set of antecedents. Geographical proximity is typically an important determinant of conflict, even in the context of firm-level rivalries as argued for instance in Yu and Canella (2007). Identity also plays an important role in the creation of a rivalry (Menon, Thompson, and Choi 2006). Finally, history and the outcomes of previous interactions are another key determinant of rivalries (Kahneman and Miller 1986; Miller and Chen 1996). All three of these factors are at play in college football. Conferences are typically comprised of comparable schools in a particular region. Fans identify with their team by wearing certain clothes and in more extreme cases with body paint and other adornments. Despite periodic conference realignment, many teams play each other year after year. Thus, we believe that in addition to being interesting in its own right, examining what drives rivalrous feelings in college football can provide insight into rivalry more generally. …