The COVID-19 pandemic of 2020 changed the way we interact and engage in commerce at a fundamental level. Social distancing and stay-at-home orders leave businesses and cities wondering what economic activity will look like in the future. Given a likely reduction in face-to-face interactions, it is important to better understand how social interactivity influences economic outcomes. Here we measure the effect of social interactions in the workforce on patent production and economic efficiency. We decompose U.S. occupations into individual work activities, determine which of those activities are associated with face-to-face interactions, and reaggregate the labor force of each U.S. metropolitan statistical area (MSA) into a metric of social interactiveness. We then calculate each MSA’s density of social work activities and find that this measure is more highly correlated with an MSA’s per capita patent production than simple population density. This suggests that density of face-to-face interactions is the important driver of a city’s rate of invention. We close by exploring analogies between the development of cities and the development of stars, suggesting ways these analogies may help frame future research on cities.