A system and method are provided for processing a request for crowd data for a large geographic area. In one embodiment, a central system, which includes one or more servers, operates to obtain current locations for users of mobile devices and form crowds of three or more users based on the current locations of the users. In order to provide access to crowd data for crowds for a large geographic area, the central system receives a request for crowd data from a requesting device, establishes a bounding region for the request, and identifies one or more starting points within the bounding region for the request. Crowds are identified, crowd data for the crowds is generated, and the crowd data is returned to the requesting device in an iterative manner for a series of two or more outwardly radiating, concentric geographic regions centered at the one or more starting points.