A geographic study of tie strength in social media

In this paper, we investigate the interplay of distance and tie strength through an examination of 20 million geo-encoded tweets collected from Twitter and 6 million user profiles. Concretely, we investigate the relationship between the strength of the tie between a pair of users, and the distance between the pair. We identify several factors -- including following, mentioning, and actively engaging in conversations with another user -- that can strongly reveal the distance between a pair of users. We find a bimodal distribution in Twitter, with one peak around 10 miles from people who live nearby, and another peak around 2500 miles, further validating Twitter's use as both a social network (with geographically nearby friends) and as a news distribution network (with very distant relationships).