Roche and colleagues report that they “examine[d] the influence of physical proximity on between-firm knowledge spillovers at one of the largest technology co-working hubs in the United States. Relying on the random assignment of office space to the hub’s 251 startups, we find that proximity positively influences knowledge spillovers. . . . This effect is largest for firms within close proximity of each other and quickly decays: firms more than 20 meters apart on the same floor are indistinguishable from…