Working paper by Arcidiacono, Ancejo, Hussey, and Spenner:
This paper examines sorting into interracial friendships at selective universities. We show signicant friendship segregation, particularly for blacks. Indeed, black friendships are no more diverse in college than in high school despite the colleges blacks attend having substantially smaller black populations. We show that part of the reason for the segregation patterns is large differences in academic background coupled with students being more likely to form friendships with those of similar academic backgrounds. Within a school, stronger academic backgrounds make interracial friendships with blacks less likely and friendships with Asians more likely. These results suggest that affirmative action admission policies at selective universities which drive a wedge between the academic characteristics of different racial groups may result in increased within school segregation.