Why do firms cluster near one another? We test Marshall's theories of industrial agglomeration by examining which industries locate near one another, or coagglomerate. We construct pairwise coagglomeration indices for US manufacturing industries from the Economic Census. We then relate...

We study how diversity evolves at a firm with entry-level and upper-level employees who vary in ability and "type" (gender or ethnicity). The ability of entry-level employees is increased by mentoring. An employ receives more mentoring when more upper-level employees have the same type. Optimal...