Studying preferences over the demographic composition of co-patrons. Racial homophily does not vary by income. These preferences can explain much of income segregation, from Victor Couture, Jonathan I. Dingel, Allison E. Green, and Jessie Handbury https://www.nber.org/papers/w33386

Allison Green's job market paper studies the role of networks in facilitating migration, using quasi-random ship assignment of US Navy sailors during World War II. allie-e-green.github.io/public/WW2_A...