Following calls for a spatial turn in communication studies, we investigate the reach and topography of Twitter communication in two case studies of Berlin and Jerusalem. We theorize on the spatial dimensions of social media communication and their potential to establish a public sphere that can reach from the local to the global level. Empirically, we investigate the scope of Twitter communication of local users in Berlin and Jerusalem and ask to what degree their interactions and issues indicate a local public sphere or extend beyond the local level. We use a combination of topic modeling and a novel localization index to explore the spatial dimensions of the two Twitterspheres. Our data point to a considerable share of locally rooted conversations, but the majority of communication reaches beyond the local. At the intersection of interactions and issues, we uncover complex, semilocal configurations of public communication.