Featured graphics Economy and Space One-sided or two-sided love? Visualizing connections between metro station pairs in Beijing Yuling Yang The University of Hong Kong, China Hanxi Ma The University of Hong Kong, China Jiangping Zhou The University of Hong Kong, China Abstract As more and more metro lines and stations have started serving our metropolises, they have (re) shaped our travels and lives, creating (new) venues and (additional) opportunities for serendip- itous contacts. To know the odds and locales of serendipitous contacts among millions of metro riders, we employ the smartcard data of the metro riders in Beijing to visualize metro riders’ identifical trip trajectories and to visualize/disclose connections between metro station pairs because of these trajectories. We find that the pairs that produce the largest and smallest num- bers of identifical trip trajectories are not randomly distributed in the city. Rather, they concen- trate in the northwest and in the central, respectively. Keywords Serendipitous contacts, smartcard data, metro, odds, locale, Beijing In cities, public spaces could contribute substantially to diverse social interactions, including serendipitous contacts (Jacobs, 2006). Serendipitous contacts occur more frequently among strangers than among acquaintances. Such contacts that are due to close physical proximity among people are referred to as one kind of co-presences (Zhao, 2003). Physical co-presences (PCPs) are a critical element of booming economy and healthy communities Corresponding author: Jiangping Zhou, The University of Hong Kong, 836 Knowles, Po Fok Lam, Hong Kong, China. Email: zhoujp@hku.hk EPA: Economy and Space 0(0) 1–3 ! The Author(s) 2019 Article reuse guidelines: sagepub.com/journals-permissions DOI: 10.1177/0308518X19866474 journals.sagepub.com/home/epn