The subject disclosure pertains to systems and methods for determining locations of mobile devices. In particular, a set of regions is defined based upon the relative strength of signals received from one or more base stations within the region. Each region has associated location information (e.g., latitude and longitude). The location of a mobile device can be determined by analyzing the strength of received signals, identifying base stations and generating an ordered list of base stations based upon signal strength. The ordered list can be compared to the set of regions to determine the region in which the mobile device is located. The location information for the retrieved region can be used to estimate the location of the mobile device.