In one embodiment, a method comprises receiving, via a mobile station, contextual information or geographic location data relating to a plurality of members of the population within the geographic region, identifying a common element in the received contextual information relating to at least two members of the population as a basis for defining a first boundary of the geofence to include the at least two members, wherein the common element is identified upon a comparison of the first and second contextual information, and defining the first boundary of the geofence.