This paper investigates the cultural ties in American sociology defined by the shared usage of cultural symbols across schools. Cultural symbols are operationalized as research focuses from the dissertations of a school’s graduates. We construct a unique pairwise dataset including 6,441 school pairs across 114 schools, detailing their dyadic relationships (e.g., geographical co-residence) and cultural proximity inferred from dissertations. We build a socio-cultural network where a school sends a tie to another when their proximity is sufficiently high. Using recent natural language processing advancements, we identify gatekeeping symbols co-used by reciprocally connected schools within the same cultural niche, differentiating them from other schools in the network. Our findings reveal two major school clusters and their research trajectories, with one representing dominant trends in relatively esoteric areas like sociology of culture, economic life, organizations, and politics and the other a more explicit focus on social problems. Employing dyadic-cluster-robust inference with school-fixed effects, we discern key determinants that shape cultural convergence and distinction, including school prestige, geographical co-residence, and institutional classification. In sum, our study proposes a pipeline for measuring the strengths and symbols of cultural ties across schools and understanding the factors that influence the development of duality between schools and schools of thought.