In 1975, a federal court ordered the desegregation of public schools in Jefferson County, KY. In order to approximately equalize the share of minorities across schools, students were assigned to a busing schedule that depended on the first letter of their last name. We use the resulting...

"We develop a Roy model of social interactions in which individuals sort into peer groups based on comparative advantage. Two key results emerge: First, when comparative advantage is the guiding principle of peer group organization, the effect of moving a student into an environment with...