A system and method are provided for forming crowds of users and providing access to corresponding crowd data. In one embodiment, a central system, which includes one or more servers, operates to obtain current locations for users of mobile devices. The system forms a crowd including a number of users based on the current locations of the number of users using a spatial crowd formation process based on an optimal inclusion distance that is a function of density of users of the plurality of users within a bounding region. The central system then generates crowd data for the crowd and provides access to the crowd data for the crowd. In one embodiment, the crowd data for the crowd includes an aggregate profile for the crowd. In another embodiment, the crowd data includes data characterizing the crowd. The central system provides access to the crowd data by serving crowd data requests.