Follower ties play a major role in many social media platforms, representing users' choices on what content to pay attention to. This Element examines the role of geography and similarity by gender, age, race, and partisanship with respect to attention in social media by studying the follower ties among 1.1 million Twitter accounts matched to U.S. voter records. We find that geographic proximity is the dominant predictor of follower ties, and that demographic similarity by age and race/ethnicity are quite important. Surprisingly, given the prominence of political polarization in the contemporary US, partisanship plays a relatively minor role. In addition, our results indicate that the tendency to follow nearby users leads to following users of the same race/ethnicity and partisanship. Our findings highlight the enduring significance of physical geography in virtual spaces and that political preference is not a dominant determinant of online attention in social media.