This chapter outlines theoretical and methodological challenges in mapping social media activity onto geographic locations, particularly the challenges in collecting relational data with spatial attributes. We discuss the role of space in tie-selection and retention in online social networks and how real-world users interact with Twittertrolls, sockpuppets, Twitterbots, and algorithmic filtering largely detached from the geographies inhabited by users. The study examines these issues by means of case studies that mapped social media activity to geographic locations and found network spillover effects where online and offline social activity reinforced each other. We conclude with a review of the existing evidence on the directionality of homophily between online and offline social networks and the spatial dimensions of social media.