  This paper studies for the first time the usage and propagation of hashtags
in a new and fundamentally different type of social media that is i) without
profiles and ii) location-based to only show nearby posted content. Our study
is based on analyzing the mobile-only Jodel microblogging app, which has an
established user base in several European countries and Saudi Arabia. All posts
are user to user anonymous (i.e., no displayed user handles) and are only
displayed in the proximity of the user's location (up to 20 km). It thereby
forms local communities and opens the question of how information propagates
within and between these communities. We tackle this question by applying
established metrics for Twitter hashtags to a ground-truth data set of Jodel
posts within Germany that spans three years. We find the usage of hashtags in
Jodel to differ from Twitter; despite embracing local communication in its
design, Jodel hashtags are mostly used country-wide.
