Abstract: A system is disclosed for customizing a geographic location index based on user preferences. The system obtains geographic data provided by a user and generates a customized geographic region based on the obtained geographic data. The system generates relationship data corresponding to the new customized geographic region. The system updates the geographic location index based on the new customized geographic region and corresponding relationship data. Thereafter, on-line content may be delivered to an audience associated with the new customized geographic region, thereby allowing the user, such as an advertiser or publisher, to define targeting regions that are optimal to their specific business environment.