An engagement tracking system monitors user interactions with media items to calculate an engagement score of the media item. The engagement tracking system may be or include a group of one or more server machines configured to detect an exposure of a client device to a media item maintained by the engagement tracking system. In response to detecting the exposure of the client device to the media item, the engagement tracking system tracks a location of the client device based on access requests to location based media items. The engagement tracking system may thereby monitor client devices exposed to the media item in order to calculate an engagement score of the media item.