17. A system comprising: a targeting system for selecting content to users, the targeting system comprising: a keyword identifier configured to identify location keywords for each of a plurality of granular locations, a geographic feature identifier configured to determine a feature size for grouping the plurality of granular locations over an area of interest, to determine geo data for each of one or more features, and to form a set of granular locations for each of the one or more features using corresponding determined geo data, each set of granular locations being from among the plurality of granular locations and being associated with a corresponding one of the one or more features, wherein, for each feature in the one or more features, the set of the granular locations that is formed is based on a threshold percentage of coverage of the plurality of granular locations by the feature, a keyword aggregator configured to generate a keyword mapping for each of the one or more features based at least in part on a set of location keywords from the identified location keywords, wherein the set of location keywords is associated with a corresponding set of granular locations, and a content selector configured to receive an indication of a user location, to determine a first one of the one or more features that includes the user location, and to select content for delivery to a user using a corresponding keyword mapping for the determined first one of the one or more features, wherein the corresponding keyword mapping for the determined first one of the one or more features is formed from a corresponding set of location keywords associated with the determined first one of the one or more features.
17. A system comprising: a targeting system for selecting content to users, the targeting system comprising: a keyword identifier configured to identify location keywords for each of a plurality of granular locations, a geographic feature identifier configured to determine a feature size for grouping the plurality of granular locations over an area of interest, to determine geo data for each of one or more features, and to form a set of granular locations for each of the one or more features using corresponding determined geo data, each set of granular locations being from among the plurality of granular locations and being associated with a corresponding one of the one or more features, wherein, for each feature in the one or more features, the set of the granular locations that is formed is based on a threshold percentage of coverage of the plurality of granular locations by the feature, a keyword aggregator configured to generate a keyword mapping for each of the one or more features based at least in part on a set of location keywords from the identified location keywords, wherein the set of location keywords is associated with a corresponding set of granular locations, and a content selector configured to receive an indication of a user location, to determine a first one of the one or more features that includes the user location, and to select content for delivery to a user using a corresponding keyword mapping for the determined first one of the one or more features, wherein the corresponding keyword mapping for the determined first one of the one or more features is formed from a corresponding set of location keywords associated with the determined first one of the one or more features. 20. The system of claim 17 , wherein: the content selector is configured to select content further using at least one of demographic or social data associated with the determined first one of the one or more features, and the corresponding keyword mapping for the determined first one of the one or more features is based on at least one of demographic or social data of the user.