Systems and methods to control the lifetime of social networking posts. The viewable range and/or duration of a post is determined as a function (e.g., Gaussian) of the viewer location/position relative to the post location/position and other factors, such as, local content density power of the poster, net likes, etc. The expiration time of the post at the viewer location/position is extended when content density is low, and reduced when content density is high. Posts are retained for a fixed duration in server; and zone-relevant content is delivered to clients based on local content density. Content from distant cells is highlighted by graphics that distinguish it from local range posts.